I often get questions from young women who are working out hard and watching every bit and still can't lose weight. They might be putting on muscle, but they are still carrying visceral fat and not feeling great overall.
There's something going on with your thyroid if you're working out ton and holding steady at 175 pounds. You could have a very muscular build, but it's also quite likely that your thyroid has become lower due to so much exercise on a low carb and low-calorie diet. Women's bodies are expert at slowing things down when there seems to be a shortage of nutrients in relation to calorie demands. It's possible you had a thyroid condition to start with, but before assuming that, it makes sense to add carbs for several months.
To give you a point of reference, I'm 38 years old and 5'7", and for exercise I currently do about 3 walks in a week, each about an hour. I then eat oatmeal, fruit, bread, whatever... and I'm about 155 pounds and a size 10 (dense build). Obviously my metabolism should be much slower than that of most people in their 20s. (And it's much slower than I remember it being in my 20s). My lean ideal weight is around 145-150 and a size 8, if I exercise more and eat more vegetables, but I'm not going for that right now.
If I go too low carb I just hit the wall and lack the energy to exercise, and when I exercise more than 3 walks a week (and nurse a toddler lol) I can eat virtually anything I want. I'm always shocked how much more food and carbs I need when I'm exercising versus sedentary. It's more than double, probably triple. If I don't eat enough carbs I feel energetic but fragile, and over time I'll start to feel unwell. This energy shortage is also part of why your cycles may be short. You might be ovulating near day 12-15, which is the normal time, but then your hormones aren't able to stay up long enough in the luteal phase to finish the full 26-30 days that a cycle would normally be. In an older person this scenario would probably lead to no menstruation at all, or missed ovulation, but if you're young your body can make the ovulation happen even when short on supplies.
Low calories can also lead to delayed ovulation and longer cycles, or irregular cycles, depending on your body's response. Women tend to see a pattern over time. For me it appears I ovulate on time or not at all, and my cycle never gets delayed. Others will end up with relatively consistent 38-40 day cycles.
If you put into a calorie-tracking app like Cronometer your typical meals for a day, you might find that you're eating less than your body might want with all the training you do. You can also find other signs. Indentations on the side of your tongue reflect what Asian medicine calls "spleen qi deficiency", or what Western medicine would call a stressed digestive system, from overthinking (typical student problem), overwork, cold and raw foods, and lack of protein and complex carbs. Thin and dry hair and skin, and low basal body temperature, can also occur when thyroid function is low. If your diet doesn't include the junk that normally contributes to cramps and clots, and you're exercising, but you're getting them anyway, it's safe to assume that your body isn't getting something it needs. In addition to eating more overall, I'd suggest a mineral supplement like NOW Liquid Minerals, and a fish oil supplement if you don't eat fish. The minerals are calming and can reduce cramping, and the fish oil can reduce inflammation.
There's also an herbal supplement called "Free and Easy Wanderer" which can reduce mood swings and stress before your period, as well as prevent some of the cramps and clots if you take it the week before. It's a standard formula which many companies make, just try to buy one made in the USA or another trusted country, and tested for lead and other additives. It's often used starting a couple of days after ovulation signs, and taking it til you start your period. Assuming you're already eating real food, and there's no need to overhaul your diet,
here are a few suggestions to add to the good framework you already have: 1) You should pick some slow carbs that you enjoy, either whole grains without gluten, or well-cooked legumes, or root vegetables like sweet potatoes and (cooked) carrots to eat every day. During your period, eating cooked, easy-to-digest foods rather than raw foods can help with nausea and discomfort. You might suspend salads and eat sauteed zucchini with garlic, roasted sweet potatoes and carrots, potato soup, etc,... for those few days.
2) Hot drinks are relaxing and nourishing. Try hot tea with cinnamon, cloves, etc,... like dairy-free chai. We use Bengal Spice tea as a chai-like tea with no caffeine, and of course there are many delicious chai teas. I simmer the tea bags in milk or milk alternative for 20 minutes and then add cream and sugar or honey. You might consider making "golden milk" with turmeric also, to reduce inflammation, improve circulation and reduce cramps. This would be good to take before and during your period, and many people take it every day because turmeric has a calming effect. 3) Add more slow carbs and even fast carbs on days when you work out. You might experiment with the timing to see if there's an ideal time (for some it's evening before bed), but for mood improvement one carb load per day can be really helpful. That means eating a carb by itself, maybe with a little fat. This takes the amino acids circulating in your blood through the barrier into your brain, so they can be converted into serotonin, the brain chemical which we consider to give feelings of happiness and emotional resilience. 4) Support your digestion after meals with kombucha, bitter herbs like horseradish or mustard, warming herbs like ginger or garlic, or hot tea. You may have breakfast digestion covered with coffee, so just make sure you have some kind of digestive aid each time you eat. Ginger chews or candy, or fresh garlic and mustard in your salad dressing can be easy ways to include these. 5) Plan your training to coincide with your cycle; give yourself heavier workouts, especially if you feel stressed, before your period, and take it easy the first few days of your period. Taking a walk is fine, but mostly recharge during your period. In general, your body might be overtrained, and it might be that a heavy workout every other day is better than a regular workout every day. Remember, too, that you might be hungry as your period wraps up and your appetite improves, so be willing to eat extra on days 4-7 of your cycle. You may want to have some healthy snacks on hand for the munchies. It's not necessary to try everything at once to get results. Pick a few elements that are doable right now and ease into it. And reach out if you would like more guidance about your particular situation. Good luck!