Wow- next time I would flat out STOP the bike and tell her she has no business telling you how to work out.
Seriously some teachers need to learn their place and this isn't one of them!
I know how you feel- I struggle too and have gone up and down. I finally stay 189 the other day only to start TOM and want to eat everything in sight since then! I'm trying to control it but there are times I just want to eat GRRR lol.
It's just trial and error honestly. I looked back to what I was going before that worked- that definitely helps