The commercial check ride is a whole lot of precision and not a whole lot of instruments. I see a lot of schools try to teach this in 10 hours and in my opinion it is just not enough time.
It's also a very out of date test these days and it is out of the natural sequence of things. That can make is more difficult for some pilots. Especially those that are really good with instruments or glass cockpits.
I found it odd that the whole commercial training and check ride is VFR with almost no instruments.
Yet, most commercial pilots fly IFR and use instruments. It never did make sense, to me, to test a commercial pilot on VFR when we normally don't fly VFR. But that is the way the FAA has it set up for the past 50 years.
With all of that being said, my opinion is that the commercial checkride is just one ride to get out of the way. You won't be flying passengers around doing lazy 8's or chandelles. However you will be asked to demonstrate at least one of these maneuvers on your commercial checkride. I used to say the commercial checkride is doing all of the things that you are not supposed to do on your private checkride. Some say it's a lot of fun. I don't agree.
Best advice I can give you, is to slow down a bit. Take about 30 days and really get this stuff. Don't rush it. The more you practice, the more confidence you will have. You probably won't use any of it again in real flying, but you will get through it.
Also once your feel you are about 80% ready, you might consider taking a week and finishing up at Shebles. They will drill the missing stuff into your thick head pretty well.
Joe