I would also take a look into Aldora divers and their Aldora Villa. I have spoken to a couple of single females who went that route and both seemed to enjoy it. I can speak highly of Aldora, but have not been to the Villa. Everything I've heard about it has been positive though, and others will chime in here with reviews I'm sure. Mary, didn't you visit Maria or someone there on your last trip? (she will answer...she lives in her too
SCC gets good reviews as well though...but I have never used them so can't speak from personal experience.
All of them will take you to the dives you speak of...it is very difficult to find a dive on Cozumel that isn't worth doing.