Should I give up and gain it all back? (hormones, period missed)

unknown

I went down from 135 lbs to 126 (I'm 5ft 4, healthy BMI) in 4 months (very slowly). I ate healthy food, vegetables, fruit, lean meats, seeds, nuts, whole grain bread/pasta, brown rice, dark chocolate in moderation, avocado, peanut butter, generally a diet that's not boring or hard for me. Every day ate at least 1500 kcal, when worked out (ran, cycled, horse riding, HIIT videos from youtube), then ate back my excersise calories.

I was happy about myself, my body composition changing... Despite all these I lost my period (5 months missed). Been to the gyno, I have no PCOS, no pregancy, more like a Hypothalamic Amenorrhea. Women usually said they had to gain weight, body fat to get their periods back. They also had to cut out ALL excersise. They gained 10-20 lbs to get their body working...

Does this mean that being lean and athletic is not for me? I've never been overweight and I've always been very active. I don't want to give up and gain back more... I already gained 5 lbs back and I'm on progesterone pill, but still no period since December 24th, 2014.

Help

unknown

Update: Yesterday I finally got a PROPER period. It's as heavy as it's been before. Though I needed to gain 4 pounds back, but I feel much better, eat at maintenance (2000 kcals daily) with a lot of healthy fats, but generally clean diet. Being for like a week back on maintenance after a month of caloric surplus I started to see my fat go away again and the scale slowly crawl back down, so I guess my TDEE is even higher than 2000. I might consider a reverse dieting and bumping my calories up until I lose no more, to find my true maintain kcals.

So girls: Try to resolve what is causing the stress and please eat more, your body will reward you and you will feel wonderful!

After finding my true TDEE I'd like to embark on a lifting programme, though not sure yet if I my parents can fund the gym membership, but will give it a try.