I have a billy kid 4 weeks old, and he was having problems latching on when his mums udder was full, I found that milking her a little first helped a lot, in fact he pushes me out when she is on the milking stand, could you try a different teat? the bottles I bought this year have quiet small ones, if you want to try another size I have some bigger ones I could pop you one over,
I had 3 to bottle feed last year but one of my girls adopted one so only had two to do in the end.