My son was a little tank as well. We bought Sterns life vest with the crotch strap. However, the Sterns children vest don't have any flotation on the back. It is all on the chest and the head flap.
He would roll over and play in the water at our zero entry pool and the vest allowed plenty of mobility. But, when he got in a little deeper water it would assist him to his back and the majority of his head out of the water.
It is a little early for your daughter, but he uses an Astrl Otter vest and it is awesome. Highest float of the children vest and super comfortable.
Congratulations to you and your wife for getting your little one out into the water.