You can order online for target and return in store if it doesn't fit ... they had some 2xls when I looked . Also stores like motherhood maternity , pea in the pod ect have a much wider variety of sizes . I also got some at khols.
I ordered a few pairs online from motherhood and they fit wonderfully.
I ordered 1x and they fit like a 16/18
My boyfriends mom got me plus sized maternity clothes from old navy and my mom got some for me from target. F2
I got one pair of leggings from Destination Maternity. The prices are high but I scored with the lowest price one. I've been using them throughout my entire pregnancy so far and no need to go get another size yet. I got some dresses from Goodwill, and Marshall's has some cute maternity shirts. Just remember, you don't have to spend a lot on these clothes. Because once the baby comes out you're not going to remain the same size. Good luck!