Sleep advice please - 15 week old

[Neiffer]

Hi
I'm just after a bit of advice really as feeling a bit lost! Ds2 is 15 weeks and our nights look a bit like this:
He goes to bed at 6:45/7ish happily
Wakes at 9ish and shouts for 5 mins then goes back to sleep
Wakes sometime between 10/11 for a feed.
Wakes at 12ish and will only settle by sucking my finger (dummy refuser) so we co sleep with him waking a few times and me sticking my finger back in his mouth until he eats again at 5ish then up for the day at 6:30ish.
My questions are:
Should I feed him at 9 even though he happily goes back to sleep after some shouting?
What can I do to break the habit of finger sucking ?! I'm loathe to just stop as this way I get some sleep as otherwise he wakes up every hour or so. I suspect he would eat but doesn't seem to need it at the same time and I don't want him to start eating more and more at night out of habit either.
Basically, how can I get him to settle back to sleep without him coming into bed and sucking my finger?! Please tell me it isn't just me that's found themselves in this odd situation! He's ebf and will not take any form of dummy :(

Or should I offer him milk every time he wakes up? Just seems counter productive to me if he'll happily sleep just sucking my finger...

I would feed at 9 and see what happens.

Yeh I would feed at 9 too and you might find that knocks out the 12 wake up. Not sure about the finger sucking - my ds is a dummy refuser too and used to settle on my little finger ... And then one night I woke up to a loud sucking noise and he had found his own finger. I try to encourage him to have his own thumb/finger in the day and this sometimes works now.