Your boyfriend is a tool. He needs to go.
Also, I think your Mum could handle the situation better, regardless if she is your Mother or not she should not be calling you "fat". She could say "Hey, why don't we join the
gym together, it could be fun!?" Or, "Wanna start walking every day?" She could encourage you to eat healthier........but, she just calls you
fat, way to go Mum! How awful!
Lose the 20
pounds when you are ready and because you want to, not because some moron guy and your rude Mother want you to.
Oh yeah, and the cucumber meals have got to stop too. Like Mal said, read around and you will learn
Good luck and keep your chin up.