Advice about my female cat?

my Q is, my cat was in heat at the end of may, she managed to get out for a few hours (Not Sure if she was with a male cat) but since then she has been drinking more water than she usually would/has, and shes been meowing for more food, i heard you can check there nipples at 3weeks gestation but i'm nt sure how pink her nipples are meant to be, she's a longish haired cat so its hard 2 tell if her belly's different or not, so i was Just looking for advice, do cats tend to drink more in pregnancy? thanks