I just feel chubby 😩 when did your belly pop with first?

I've been small my whole life. I'm 5ft and the most I've weighed was 117lbs in college.  Before I got pregnant I was 105 and fit and now I feel like I just look chubby and not pregnant. I have my engagement party in 2 weeks and everyone knows I'm pregnant but I want to actually look pregnant and not like I just gained weight! I'll be 18 weeks at the party. Is it possible that my belly will pop in the next 2 weeks?? I posted the picture below to show the difference which is why I just feel like I look like I gained weight and don't actually "look" pregnant.