It is not unusual that one will see this irregular schedule of menstruation, especially early on in the teenage years of menstruation.
I'm sorry but your polycystic ovaries are not due to "stress" or "bad eating habits" and living a stress free life and eating better...while positive changes...won't really help.
As strange as it sounds if a female is not sexually active but often getting on hormone containing birth control will result in a more regular schedule of bleeding. That's because the hormones in these control when bleeding occurs.
Since we cannot see your legs on the internet, we cannot diagnose whether they are varicose or not. However, it is unlikely.
There are many arteries/veins near the surface of the skin (one notices veins more as they are carrying blood without oxygen back to the heart and appear darker than the oxygen risk arteries) and when someone works out (and thus needs more oxygen to muscles) these can expand a bit.
If you're lost fat in certain areas, these veins can certainly appear more prominent; this does not mean they are varicose veins. You are likely to notice these veins more since you've lost weight (I did when when I lost some).
Varicose veins often tend to cause pain the area. Not muscle pain; actual pain from these veins themselves. If no pain, it's again, unlikely you have these and perhaps you're just noticing the veins more now with the weight loss and the working out.
It's important to realize that a menstrual period is more than just bleeding; it is the sloughing off of the uterine lining which has built up during the cycle and is not needed since conception did not occur. The clots that you see are these pieces of this lining.
If the bleeding is very severe you might run the risk of become anemic over time (low iron is the number one nutritional deficiency of women of child bearing age). Sometimes a physician will put a woman on birth control pills to lessen the bleeding and avoid this. If these symptoms continue it is probably a good idea to make an appointment with your Gynecologist to discuss these symptoms with them.