Ouch, that's a pretty scary situation.
You can always regain width, so don't worry about that too much; dilate with whatever will fit, even if it's smaller than your finger at first. If you can document that you still have most of the original depth, that's very good news, because all you need to do is repeat the regimen that's used early post-op to gain width - start with a tiny dilator, move up to adding a slightly larger one when you feel ready but use the smallest as the first in the session to get you prepped, and keep repeating that cycle with progressively larger dilators.
There are also dilators intended for women with vaginismus that are very, very narrow, if you want to find something like that. But your surgeon may well be able to recommend both the tools and the schedule for you, and I'd definitely at least try asking.