Are you block feeding also? I would try hand expressing through the initial letdown, till the flow slows down.
It is generally time that will fix this, as your supply settles and baby gets bigger. Both of mine have struggled with letdown early on, but by 10 weeks or so they seem ok with it.
Have you called the ABA for advice? 1800-686-2-686. I'm not sure how using a bottle would help? Wouldn't that be even faster?