I have made several worlds with the same result. My biomes either end up as an island surrounding by a endless ocean or a Frozen one. I think its cool to be on an island but I do not want to at the moment and the whole frozen endless ocean is annoying. I have uploaded some screens to show what it looks like.
Okay It isn't Biomes O Plenty that is causing the problem. It was Better World Generation which is strange because I thought I had it disabled. This thread can be closed now.
Here:http://imgur.com/a/gyC1H