Weight gain

Yall I don’t even know where to start this because I came home crying after the drs office I had my very last weigh in and I really tried, I cut out soda , I don’t snack at night , I usually eat the same thing all week and limit what I eat I don’t really drink anything all day expect water but yet I GAINED weight and I’m like how ?? I haven’t been over eating , I’ve been watching my stuff not eating out like I’m honestly so frustrated because before when I wasnt even trying to I lost weight quick so like I don’t even know how I’m gaining so fast