Clothes - maternity/plus size

Amber

Hi guys I'm looking to buy a winter coat I'm generally skinny but most my coats are usually size 12-14 im looking to get one soon and want it to last. Do you think its worth me getting like a size 18?? For when i gain weight around 6months and my belly is really out? Or did you not bother? Help I want to buy a long jacket because its so cold. Let me know your thoughts?