I did a trip to Bonaire in April of this year... fantastic spot! Can highly recommend Captain Don's Habitat for accomodation. If you are into underwater photography they have a very knowledgeable Swiss man running a photo lab onsite. They do quite a few slide shows and run competitions too.
I was also freediving by myself (past tense now, lesson learnt) and had an absolute ball on the reefs. It is such a perfect island. Visibility varied between 20-30m. I'm sure you'll find the depths you're after. Their dive crew didn't mind freedivers on their boat either.
Enjoy
It's definately a place I'd return to.
