A couple of comments: before descending make certain that air is not trapped in wet suit. I get vertical on the surface and pull out on waist belt to release any air trapped in legs. Also a new or seldomly used wet suit needs a little convincing. And buoyancy check needs to be done with a tank that is nearly empty (500 psi) at ten or 15 feet. The air you breathe from a 80 cu.ft. tank weighs a little less than 6 lbs. In other words you need to be about 4 - 6 lbs "heavy" at the beginning of the dive to have enough weight at the end of the dive to maintain a safety stop without popping to the surface.
Don't discount the wetsuit issue. It happens more than people think.