Really struggling with body changes, weight gain, and comments from others, and my partner has been so unhelpful

I'm 25 weeks at the moment and have always been slim but worked hard on my body in the gym etc. I knew having to go through pregnancy changes would challenge me in the body image department but I didn't expect to gain so much weight so fast (18lbs and counting) and people seem to feel like they have a right to comment on it every time they see me. 'You're so big', 'you look SO pregnant' etc. Couple this with my face becoming a circle, chafing that doesn't let up even when I'm in bed, and none of the maternity clothes that I bought even a few weeks ago fitting me right, I just feel disgusting. I honestly don't want to be touched or leave the house and I can feel people I know looking me up and down. I want to escape my body but not only am I probably going to get bigger but I'm now really starting to fear what I'll be left with post partum.

I've tried telling my partner how I feel and he said we should buy some bigger clothes and that he wishes I was happier about being pregnant. I've said I am happy about it and often say as much, I'm JUST struggling mentally with the changes to my body more than I thought I would, and he just goes quiet and says he doesn't know what else to say.

I can't talk to my family about it because I grew up in a toxic 90s household where everyone was on a diet and bitching about other people's weight so I don't think I'll find any sympathy there, and I'm the first of my close friends to have a baby.

I'm just so frustrated that I can't accept what's happening to my body, I feel so guilty but I truly want to crawl out of my own skin. I'm so sick of comments from others too and just wanted a little bit more emotional validation from my partner but I really don't think guys get it.

What can I say to him to get him to understand why I cry every time I have to get dressed and go somewhere?