I would definitely lighten your load, especially if you are fresh out of highschool or entering/returning to college after a long time out of an academic environment. As you get into the swing of things, get your study habits fine tuned, and feel less strained then I would gradually increase my load.
I took A&P I with a lab, Micro with a lab, Nursing I with clinicals twice a week, and Pharmacology all in the same semester and I literally had no life, little time for eating and sleeping etc. in between class time, clinical time, care plans
and study time to maintain my grades. I got wiser the second semester and knocked off quite a bit on my schedule. I know you want to get things done as fast as possible, get that degree and get out into the workforce! Believe me! I felt the same way, but sometimes its better to take things slow especially if you are having trouble keeping your grades up. Its very important you master and retain the information because you will DEFINITELY be applying it each day.
And the whole four years at a CC thing...the '2 year ADN' is quite misleading. Please visit the nursing student forums and just browse through the threads. Most CC students, myself included, spend 3+ years working on their ADN when you count pre-req's, waiting time for acceptance into a program, and/or lifestyle constraints (having to work full time and raise children, etc.)
Don't drop out. It is completely doable! Just take it one step at a time and don't try and do too much at one time. Set yourself up for success, not failure. Good luck!