No, it is not too late to go back to breastfeeding. Some women are able to relactate months after they quit. In your case it should be doable
as you mentioned you still have milk.
You can decide if you want to combine formula feeding with breastfeeding, a lot of women do this, they nurse when they are at home and formula feed while shopping or in the evening so husband can have his share as well. It is basically up to you to decide. You can also eventually go back to exclusive nursing if you decide to work on increasing your supply.
To increase your supply you will need to offer your breast as often as your baby is hungry, yes, that means feeding on demand right now. In order to up your supply, which is still there, as you said, but probably too low to exclusively satisfy your baby's needs, you would need to offer your breast
first each time you feed your daughter, then, if she is still hungry, offer her formula. There is such thing as a Haberman bottle system which you can put on your breast so while she is getting her food basically from a bottle of formula, she has to suck your nipple to stimulate it and work on your supply.
It can take time to get your supply back. But even if you decide to do breastfeeding only a couple of times a day, she will still have great benefits from that, it is very rewarding for both mom and a baby. Don't forget to drink plenty of water and eat a balanced diet, you will need some extra callories.
Good luck and let us know
.