I can share a few thoughts from my experiences. I too haven't had a cycle since August 2007. Likely due to a major life trauma, overtraining and under-eating (but not starving in any way). I also used to suffer terribly with PMS, mood swings and extreme pain caused by endometriosis and would be out for almost a week each month with crippling cramps. I agree with you, it is nice to feel "functional" every day of the month! My past symptoms are a big reason why I have really only given rather half assed attempts at restoring my cycle. Here's a list of potential issues.
-Osteo Get a bone scan every 3 yrs to be sure you have good reserves. Recent research has shown Calcium to be totally ineffective in increasing bone density so don't waste your $. Vit D, on the other hand is important to take. Recommended dosages are 4000IU/day.
- Take good care of your skin. Low estrogen for prolonged periods of time can cause lack of elasticity, premature aging ect. I take gelatin everyday and use good amounts of sunscreen on my face, neck and chest.
- Vaginal atrophy may also occur as tissues dry out and get less elastic. This can cause pain and frequent UTI's. Lack of libido may also occur in combination.
- Brain fog and fatigue. Caused by low hormone levels. In the long term (happened to me year 5) your body actually makes it almost impossible to train at high levels because it just conks out.
Take care of your body. While, your right, cycling isn't the be all and end all of womanhood, it is important to make sure you have the hormones that will sustain you for a happy, healthy long life.
I hope this helps. I too, would love to hear from others with similar stories.