Is it blood pressure or the medicine that is causing excessive amounts of fluid on my legs? Currently taking carvedilol, clonidine, and furosemide.

Could be. There are some blood pressure medicines like amlodipine that can cause leg swelling. The three you listed from my experience shouldn't do that. There's probably some other process that's causing that.
Either, both, other. Swelling of the legs can occur for a variety of reasons.Someone on Clonidine likely has had blood pressure that has been very difficult to control.This can stiffen or enlarge the heart & fluid can back up into the lungs or rest of body, settling in the legs.Congestive heart failure can do the same. Lung diseases (eg. Copd) can cause leg swelling. Bad veins can. Carvedilol and Clonidine can too.
Fluid in legs. These particular medicines do not usually cause significant leg swelling. Of the 3, the Carvedilol is the one that could. The other possibility you have to consider is that the condition that is being treated with these 3 medicines may be causing the problem. Another possibility is the the veins in your legs are getting weak. A doctor's visit should be able to answer this question for you.