I have baby fine hair too. I got so tired of keeping it short, I let it grow. I keep it around my collarbone and just occasionally trim the ends to keep it healthy.
When I let it grow longer it doesn't have much body. What works really well (for me) is getting a body wave, with medium size rollers. (Not a perm, I did that once, and I looked like little orphan Annie - it was horrible, I actually cried after I left the salon). So if you've never tried a body wave, you might like it, it gives my hair added fullness (without the tight curls) and a bit of lift on the top of my head too. It lasts for about 90 days, then you need to do it again (if you want to).