If latch is still not great, I'd suggest first looking at that as a cause of the oversupply/fast flow. It does happen that way. Baby's overcompensate sometimes when they can't feed well. Was the LC helpful, could you see them again? Sometimes ties regrow or need further attention.

For block feeding, you pick a period of time and feed on one side only for the duration. 3-4 hours, or whatever. But watch the other for signs of blockages just in case. And always, always watch the baby to be sure that she's still getting plenty of milk. You just do it for a few days or so till supply settles then go back to feeding however baby wants.

At 10 weeks she can probably feed very quickly. The caveat is, as always, that you're getting those indicators of good intake - wet nappies, alertness, weight gain, etc. If she's ok, then she's ok and you're doing well.

It can be a bit of a muddle at first, but that's no different to any other aspect of parenting! You just figure it out as you go and very often it's not perfect. That's just life. Doesn't mean you're not doing a great job.