My crazy mother...help!?

okay, I love my mom and she is an amazing mother. so im not trying to bash her, more like I just need to vent. ok, i'm 19 and when I was in 3rd grade my thyroid died so I gained a lot of weight. well it didnt get discovered til I was 12 or 13. well my mom would always say i needed to get thinner but she wasnt crazy about it. I ended uo losing a lot of weight on my own. and when I was in 10th grade, I was a little chubby but nothing too bad. well my boyfriend at the time left me for my best friend and said it was cause she had a better body (and because she put out) well I had felt like the while word was against me so i turned to my mom. ever since then she has pretty much freaked out every single time I eat! If she sees me eating breakfast she'll say things like 'alright, no more food the rest of the day. you dont wanna be fat again do you?' even on thnksgiving she told me not to eat more than one slice of turkey and veggies! I'm 19! I'm thin now and shes scared I'll get fat again,