Could you be pruning the flower buds off?

As already said, best if you leave it alone for the time being. You could be pruning the fruiting buds off, the frosts could be taking the blossom and also Bramley is a 'triploid' variety so you need two other apple trees that flower at the same time to get a good polination.

It can take quite a time before new apple trees start blooming and bearing fruit anyway. How old is your tree? Ours were about 5 years old before we got a crop worth picking. I'd definitely go with Moongrower's theory, and, as JTO says, frost probably hasn't helped. The lack of other pollinators is a very valid point, too. So buy some more trees and try a healthy dose of neglect for a couple of years!