How do you plan your belly size?! I'm not sure what to buy

I planned a trip for August (I'm 18 weeks now and will be 25 during the trip) and have been trying to look for swimsuits. My stomach has been absolutely destroyed from my last pregnant so theres no way I'm wearing a two piece and mesh is too see through. Anyways, how did you all go about buying clothes? Did you strictly stick with maternity or did you bump up a size. Ugh idk