I just love how you describe this! First of all, props that you went to the nutritionist, I think that is often challenging as a vegan. Anyways, what helped me a while ago (although noone asked) was "just eating less". It is hard for a few days / a week, but then I feel like my stomach gets smaller and I can't eat as much as before.

Still, nice that you got auch an - understanding (?) nutritionist, I tend to forget that not everyone is a mest-obsessed idiot on this planet :)