Where to buy play and sleep clothes?

My baby is almost 3 months and weighs about 14 lbs. I bought clothes yesterday (the play and sleep onesies that you just zip up or on all the way, which I love!) at Baby's R Us but they are too small after washing them just so he can wear them! I got 3/6 months which says it's for 13 lbs to 17 lbs. First off, where can I get these but bigger. I dont want to get the 6/9 months size bec he doesn't like them too long, his feet get stuck when he kicks around. But if I cant find any, I might have to just get the 6/9 months. Where can I get cute designs/prints and colors but good size at a reasonable price. I found some at Target for 6 months old and they are just exact size for him (seems small for that size, if you ask me). Any stores online I can look at? I dont have time to go to the mall or big dept stores. Thanks.