I don't think there's any real rule as to how many sets, as it varies from one person to another. Most of the time for people who train seriously and aren't gaining its either down to diet or overtraining. Your def not undertraining. Whats your diet like? are you getting enough protien etc? Would be worth having a read in the diet section, and if you have any questions about that ask them in that thread.
If your doing a warm up set of each exercise, then you'll be doing 4 sets anyhow. Its not about the lenght of time you spend in the gym, but what you get done while your there. A 30 minute high intensity workout can be more productive than an 1 1/2 hour workout.
Each person works differently, and it's about finding what works best for you as an individual. When I look back on my training routines from yrs ago, I was def overtraining, and not eating any where near enough protien. I used to read all the bodybuilding mags from cover to cover. It must have taken me about 4-5 yrs to find the routine that suited me best

Also, biceps for example are a very small muscle in comparison to a muscle like your quads. For a relative begginer a good warm up then 3 solid high intesity sets of barbel curls, then 3 simliar sets of dumbel curls will be ideal in my opinion. They are the 2 best mass builders and hit both functions of the bicep, the raising of the forearm and the twisting inward of the wrist.
I would def reintroduce squats, as they are the single biggest mass building exercise you can do, and can trigure a good anabolic effect in the body. Do these with leg presses. Both heavy and real strict.
Good luck with the training, and have a good read in diet section to see how yours compares to others etc.