I've only had it for a month but I really love it - definitely a happy transition. I was lucky that the 2nd bike I sat on was a perfect fit - the Trek Madone. On the first bike I tried, I felt like you said you did on your step-dd's bike - everything felt weird and wrong. But on the Madone it all felt right. So definitely try a few different bikes and maybe you'll find one that feels like butter.
The first several rides I was kinda like "whoa.... whhhhoooooaaaaa" all shaky and scared. But that feeling didn't last long. This morning i was approaching 30 mph down a hill and did not feel shaky at all.
~ working mom to 3 little girls ~
Roadie... 2010 54cm Trek Madone 4.5, Bontrager inForm