Can't seem to fight the blues

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I have been battling my weight since I was 15 years old. I lost 74 lbs about 10 years ago, and I have been maintaining ever since (give or take some fluctuation). I have recently dropped to my smallest size yet, but now I am gaining week over week, when I haven't changed a thing. I felt very sad and discouraged today, and would like to know if anyone can help me get past this emotional hurdle. Some days, actually most days, I wish I was normal. It becomes exhausting being me some days, working out, measuring all my food, having a weekly personal trainer, eating low carb/low sugar, and watching everyone else around me enjoy life and stay skinny while eating cake. I just had a complete melt down today when I had a pile of clothes on my bed that now with my 5 - 6 lb gain over the past 2 months fit me differently. My husband keeps saying it's because of my personal trainer who pushes me to do lots of squats, lunges, push ups, burpees and crazy calisthenics is building muscle. But I just feel very discouraged and sometimes just want to say, you win to my battle with weight.