Okaaayyy....how big was the dam??? :D :D Was she at the small, medium, or large end of the breed standards? Can you call up your breeder & ask?
Actually Bailey should be around 50% of his fullgrown size around now. You could double him & add a little more for comfort. Personally, I think it's difficult to find something that will be too large for him when he reaches adult. My girls are small, but they use med/large sized dog beds to stretch out on. Lazing around is what a dog does best :D
Hope this helps give you some ideas .. good luck