Suddenly refusing feeds

[Alias]

It took me almost 2 months to convince my little boy that he likes formula (bottles were ok, as long as it was EBM) and eventually about 2/3 weeks ago he started taking them no problem. Until then I was feeding him in his sleep! Great, because I go back to work in a week. Last week I stopped BFing entirely (I'd kept the morning feed) and then a few days later he started refusing his bottles. I put it down to the two teeth than came through the same day, but it's now 5 days and he's still only taking bottles in his sleep. Anyone experienced this and have any suggestions for me? I'm wondering if I go up a teat size would that help (he's on Avent 3 still)