Okay Black is one of the less worked on colors so they are often smaller, and one is a light gray, so I don't expect a monster, and the last sounds like a steel, and on average steels aren't really large either. Granted, I have seen very large specimens in all these colors, but they are the exception not the rule. I was afraid you were going to say you had sandies, then I would have been worried. Sandies are by far the largest, and REW's that have Sandies behind them, I've seen those hit 25lbs. I've been thinking about this, and I think that my light grays were on average 7 to 9 lbs at 6 months, with the occasional smaller and larger one. As adults they ran 14 to 16lbs, and continued to grow/gain weight often up to and over a year old. Rule of thumb for breeding Flemish does is at 11 months, because you want to let them grow to full potential. NZW's on the other hand grow fast and big and heavy, and mature much quicker, their heavier because they are a meat breed, which quite frankly Flemish are not. Very different breeds, one slow growing, slow maturing with very marked size differences in the colors, and one fast growing, meaty, and rather 'cookie cutter'. Relax, I don't think there's anything wrong with your rabbits, your buck is just on the small side. Since this guy is your friend when its time to breed your does maybe he'll let you use the biggest buck he has if your unhappy with your buck, thats what I would do. In the meantime just enjoy them, they are wonderful rabbits, so much more interesting than the very 'Vanilla' NZW's. Good Luck!!