I don't recommend any of the swimsuits that have the floatation devices built in. I have never seen one on a kid that didn't completely ride up into their face when the got into the water. Truthfully, the same with a life jacket. They are good to save a life, of course, but for freedom of movement and maneuvering, not so good.
We did use the Swim Trainers that had the removable inserts for the childs independence level, and they weren't horrible, but read on for my recommendation.
Last year, we stumbled across the Puddle Jumper by Stearns. It is actually certified by the US Coast Guard to have properties of a life vest, but made in such a way that it's far more conducive to swimming. Here's a link to the website. If you go to the bottom, and click on MultiMedia Views, it actually plays a video of kids jumping into a lake and swimming in the Puddle Jumpers.
http://www.stearnsflotation.com/Basic-Puddle-Jumpertrade-...
Walmart and Target sell them and they are relatively inexpensive. The nice thing about them is that they go under the child's arms, so naturally, the water keeps it on by pushing it up, but it can't go up higher than the chest, which is great for safety and freedom of movement.
My only concern would be that your daughter might still be a little small for it. I think the weight range is 30-50 lbs. But if I were you, I'd definitely look into it. They have a "Basic" model and "Deluxe" model that is about $5 more, but I have yet to figure out what the difference is... might be worth investigating. May have something to do with weight range? Not sure.
Hope this helps!