Wow Congrats!!!
I think I know how you feel, I'm not postitive, but I think when I reached my goal, somewhere in the back of my mind, I thought, Oh my god, I'm finished, will it all come back on now??? Silly but I was a tad nervous. I am under goal and have been since about 3 weeks agter reaching my goal, but I really did'nt try. Also I really did'nt think in the beginning I'd ever reach my goal, so I did'nt put a whole lot fo thought into it. So at 135 now for 5'3" I seem just right.
Your 5'1" I'd stay at 120 any lower and you could look unhealthy, no one wants that, it aint pretty :>)

Be sure and read through the other threads here, there is some good info for Maintainers.

Cheers Kathy