Well I have been riding for about a month now and it seems like I am stuck at a 12-14mph average over mostly flat/very mild incline ground. It just seems like every time I up it to 14 mph, the next day I am only able to manage 12.5, then by the time I manage to get to 14 again, I can only manage 12 the next day.
I'm wondering if maybe I am doing something wrong? Should I be trying other exercises instead of just riding? I am limited on strength training, because I have an umbilical hernia...
I've been riding 4-5 days a week usually about 12-17 miles. My main goal right now is to lose some more weight, but it would be nice to see some speed increases too. Is my train of thought flawed in thinking I can make any significant performance increases, while my body is in a mostly catabolic state?

My goal would be to be able to average 17mph over flat ground for an hour by the end of this year? Is that realistic?