Firstly, the bottle might not be necessary. Try him on a cup. Babies can lap milk up like little kittens if they need it. If he still rejects it, he's probably just happy to wait for you. At that age my DD could go for more than six hours without a bf and it sounds like he might just be timing his breaks to coincide with when you aren't there. As long as he's making up for it when you're around and your DP has EBM 'just in case' and offers it, he's probably fine.

If his weight gain is good and he has plenty of wet and dirty nappies, I'd relax and keep your expressed milk just in case.

As for the dodgy bb... Most women have a baby that prefers one side over the other. So that I could encourage DD to keep using my LHS at all, I would offer it first (she never usually lasted very long on that side as it didn't let down as fast), offer RHS, then switch her to a football hold and re-offer the LHS. She still never fed as much from the LHS, but I thought it was at least evening it up a bit. Women can successfully bf from only one side, the other will just adjust to supply him more. So you don't need to worry about it, as such. You could try expressing just a little right before you feed him, so that he doesn't have to wait, but I was never organised enough to give that one a go!

Pumping afterwards might also help to build the supply up, but if it's extra that he doesn't need (thanks to the other side), you might just find you end up with a larger stash of EBM!

GL and let us know how you're going.