Hello everyone, is there anyone here who barely gained weight during p…

Hello everyone, is there anyone here who barely gained weight during pregnancy? I'm almost 24 weeks pregnant, weighing 48 kg, and before pregnancy I was 45-46. I can say that I'm not gaining any weight at all, even though I eat normally (the only thing I can't eat is meat). The doctor doesn't say much, and I think it's not normal ? And my belly is very small, although when they measured me, they didn't say anything. How can I gain weight? Maybe there's some special kind of diet so I could gain a little bit, or is this normal?