I do NOT think 6 miles is miniscule. For me the first 3-4 miles are when my legs feel like lead, or like I'm biking through molasses. Once I'm warmed up I'm fine for a dozen or two more, but the thought of doing the first 6, over and over, is pretty daunting.

Sounds like you're doing great! And I'm glad to hear the biopsies and so on are coming back negative!