If you're doing 4 miles in 30 minutes, that's great!!! it sounds like the bike is way too big for you; you need a bike that fits better so you can be comfortable. When I stop, i have to lean my bike over to get my foot on the ground, but it's almost unnoticeable. ON the other hand, I CAN stand and straddle my bike if I have to. As tall as you are, there are a lot of bike options out there for you.
Good luck and welcome to TE.