So sorry she is suffering with 2yr molars
I am sure this is not what you want to hear but here it was unsettled sleep for an entire year!! We literally had a break for about 3 days after the canines stopped hurting then the molars started and it was awful. Meds before BT and dream meds (if you can) may help. I used ibuprofen pre BT and paracetamol after Bt when I could, my LO wouldn't always take meds after BT as he got too upset to take it.
Some people (even me a few times) can manage a dreams meds by putting a syringe into LOs mouth and letting them take it like a DF.
Sounds like you are doing everything you possibly can for her.
As you are expecting another LO I think I'd continue to get Daddy involved...how about he stays in the room with both of you and gives verbal reassurance, a key phrase repeated like a mantra, so that you can gradually wean your presence? If you have the opportunity to try it I'd prob do a couple of nights with you both there with you doing everything as you have so far but with Daddy present and verbally reassuring, then night 3 you tell her you need the toilet but will come back, Daddy stays and you leave the room and return a few mins later. Next night same, then tell her you need to go tidy the laundry or something and will come back to check on her. Leave her longer (with Daddy) but do go back.
You might also find a more instructional (though not unpleasant) tone might help with a key phrase, something like "everything's all right, go to sleep." My LO seemed to respond quite well to instruction rather than 'just' reassurance.
I'm just trying to give you some ideas as you will obviously need to be able to leave the room when baby comes and your DD will need to accept Daddy as a source of comfort as well as you.