Hi there RMJ - welcome to BW!!
Well, I don't think I will be of much help, but just want to say that I have been there. I went back to work when our DD was 4.5 months old and she started waking up for 2.5 hour night parties all bright eyed and bushy tailed and this lasted for months, coupled with erratic frequent wakings after that until time to get up.... ho hum
not a lot of fun for all involved. So, please have some big ((((hugs))) first of all.
It certainly sounds as if your LO knows how to get herself to sleep, but she seems to be having a struggle to get back to sleep in the middle of the night without a feed.
You probably realise that she has built up a habit of feeding in the night and that this is a self-perpetuating cycle - if you feed her, her body will want fed at that same time every night, so it is not as if she can do anything to stop herself, iykwim.
There are lots of things you could try, so here are some ideas:
1. This worked for us really quite well: watering down the night milk feeds. You can do this as quickly or as slowly as you feel comfortable doing. Basically, start off with full formula, then the next night, use, say 5 scoops in 6oz of water, the next night 4 scoops in 6 oz water and so on and so on until you are just offering water. Many LOs will decide that they can't be bothered to wake up for water and so will stop waking up. Not all LOs will, though and some will just totally reject the night time water. (sorry, this is assuming you are bottle feeding). We did this, but instead of changing the mix of water / formula every night, we literally did this every week or every few weeks, so it did take us many, many months. I know of one mum on this site who changed the mix every 3 nights.
2. If you are breastfeeding, offer shorter and shorter feeds every night - say, 10 mins first night, 9 the next and so on and so on. The idea is the same as 1 - maybe the LO will not bother waking for the feed in the end.
The above suggestions may or may not stop the night wakings altogether, but, IMO, may be worth trying as a first resort. If anything, they will help your LO's body to adapt to taking fewer calories in the night and then taking more in the day time.
Another method of reducing night time calories is deciding on a time (say 2.30am) that you will NOT feed beforehand (at least since initial bedtime anyway!). If your LO wakes before then, you do what it takes to try and keep them calm / get them back to sleep (even rocking / dummy etc) until the deadline, then you feed them and help them settle back to sleep. You gradually move that time later and later - 3am, 3.30am etc etc until you eventually get your LO not feeding in the night. Takes stamina and persistence, but may lead to no night wakings after a while.
If you find that you can eliminate the night feeding but your LO is still waking up, you may need to move on to what is known as pick up / put down (or using what is known as pat / shh) to help your LO to settle. Actually, you should use pat/shh first before trying pick up / put down. Pat / shh and pick up / put down are referenced in a lot of detail on this site - let me know if you can't find where (sorry, I am not very good at cross-referencing).
The basic premise is that you pat your LO on the back and say shhhh quite loudly whilst they are in their cot / crib to help them settle without a feed or a dummy or whatever. If this does not work (you need to give it a good chance though) you could move on to pick up / put down (PU/PD).
PU/PD is basically where, if yor LO wakes up and is crying, you go in and pick them up and hold them in your arms. The second they settle / stop crying you put them back in their bed. If they cry again, you pick them up then put them down as soon as they have stopped crying. The idea is you help them to soothe themselves in their bed without your help, but you are there supporting them through this. You PU/PD as many times as it takes to get them to sleep. There will likely be tears, so a tough option if you want quiet for your 2 year old, but works really, really well if you are consistent.
I know I haven't explained these last two particularly well - as I say, if you can't find the info you want, let me know / someone else who is much better as cross-referencing / explaining will help.!!!
Best wishes and let me know what you decide to do.
Frances
xx