Some days she takes 2 45 min naps. Most days, 1 70 min nap and 1 40 min
^ These nap lengths are the main clue - with a sleep cycle of ~40-45min which is typical and clearly what you have here, she's undertired when she's going for her nap. Given how she's going with two shorter naps, she'll probably only take one long nap and a catnap to get her through to bedtime. Feeding her will not make her sleep longer if she's not tired, though I can see that she's going a long time without eating, so it might be worth shifting solids a bit later or adding a quick nurse.
Since A times vary a lot at this age, its probably best to increase little by little if day-care will work with you. I'd try that first nap at 10:45 for a week, then 11 for a week if her naps haven't extended. 4hr should be reasonable at this age. You're looking really for a nap length approaching 1.5hr if not a little more than that. She'll move to one nap eventually and you don't want to be teaching a toddler how to take a long nap again (trust me, BTDT), so its important to keep her body in the habit of taking a long nap so she's not going to get as overtired when she goes to one nap.
Your routine may look more like this:
7 - WU, milk
9:30 - snack
11 - nap
12:30 - wake, milk
2:30 - snack
3:45 nap (aiming for an UT nap so she's easier to wake but may have to move later if she starts to refuse the nap)
4:30 - wake (easiest to just go in at 40min and wake her as she stirs - less crying for you as its less horrible to be worked in light sleep than in the middle of a sleep cycle)
BT - still asleep by 7-7:30
Once she's getting a restorative nap in the day somewhere, she should be able to stay up that bit later and not fall asleep nursing at 6:30.