I think at 12 months it's common (and fine) for LOs to just have two milk feeds/drinks per day. If your BFing though then 3 BFs is, IMO, still perfectly fine (and beneficial!) too
However, if you wanted to drop a BF, and were still giving her two BFs/day, then you wouldn't *have* to swap that BF with cows milk. 2 BFs would be enough milk.
It would be completely up to you which BF you chose to drop.
One option could be to drop the one at 12.45 and replace it with lunch (around 12.30 maybe?). You could also bring breakfast earlier and have it closer to her WU time (after that first BF).
She then might get peckish in the afternoon though and you could either offer a snack or bring that 2nd BF (and possibly supper too) a bit earlier.
Another option could be to do lunch before nap, and have her 2nd BF after her nap, and bring supper/dinner a bit earlier.
At 12 mos my LOs were doing a routine something like:
6.30/7am WU and BF
7.00/7.30 am breakfast
10.00 water and small snack
2.30/3.00 water and small snack
6/6.30 BF/cows milk (DD1 had cows milk at 12 months for this feed, but DD2 still had a BF).
Of course, you don't have to do the same, it's really up to you though and whatever works best for you and your LO's routine. If she's getting 3 meals/day plus 2-3 milk feeds (BF or cows milk), whenever they come, that sounds just right to me