Hi!
I'm not an expert on this but I think it sounds quite normal for a 3 mo to wake twice during the night for a feed on that routine. Especially as you're not doing a df. Going from 7:00 to 1:45 sounds very good to me at that age, and normally they only do one long stretch in 24 hrs. It is possible that if you did a df around 11 she'd make it til the morning, so that could be one option to try.
I don't know about if it could change things going onto a 3.5/4 hr EASY, so I'll leave that for someone else to answer.
Also seems like if you've not had a dummy before you shouldn't ned to introduce one now just for the sake of weaning off a NW, but it depends on what you want.
Can sympathise on not wanting to wake a sleeping toddler!
Bye for now!