What could be the cause of unexplained weight gain in a migraine patient when all the reports are normal ?

hi. in last 2 yrs i have gained 30kg for unexplained reasons which left me very upset. i started going to a personal trainer 4xp.w and making very healthy choices food wise and i still lost no weight.i went to endocrinologist when my weight kept creeping up and i did 2x urinary cortisol tests, the first aamount was 157 which doc said was high so i had scan of both brain and adrenals and lung and no tumour was found so doctor order 2nd free cortisol, this time my results were 491, i am 29 female and until 4 weeks ago i was on no medication at all, i am now on topomax 100 for migraine . now that cushings syndrome has been ruled out, what else could be giving me these results and causeing my weight gain.also my blood pressure is normal(normally it used to be low) it is causing depression now cause i just dont feel like myself!!!also my hair has become very brittle and is breaking off and gotten alot finer. im losing hair, no bald spots just less volume. and also my periods have all but stopped for the last 6 months. sometimes its weeks late, then it comes and only lasts a day. all my adult life i have always had regular periods. my skin is also got very dry and snakskin like!!!! please help