I'm not an expert, but to me all that matters is what you feel comfortable on. I'm hardly 5'2 and I've only ever ridden bigger horses. Mine is just over 16hh, and I've been 17hh and taller. I don't like riding smaller horses, personally, even if I am a bit short. I just feel more comfortable with bigger horses, which I think is what you should go with. Obviously, it shouldn't be too small, because you can get there...but yeah. (:
I agree - what you feel comfortable on. My mom was 5' nothing and rode anything she could get on. I'm 5'9" and, while I will ride any size, I wouldn't own anything smaller than 14.5 hh for my own purposes.
Weight is a better guide as to what sized horses you should ride. Height, ok, you might look silly on a little pony but if you're skinny, you won't hurt the pony by being too heavy. A general guide is that you can only just see over their wither. I am 156cms and using this guide, horses 14.1-15.0 are a good size for me. However, this doesn't mean I couldn't ride larger or smaller horses - I could. I'm not sure what range of sizes would be good for you though - I wouldn't stress to much about it. Most horses of 15hh and over can carry the averaged sized adult quite comfortable.
I'm 5'1" and my guys are 15.0 and 15.1. Although I have ridden much larger horses, I would say my comfort range is between 14.2 and 16.0 hands (those bigger ones are so hard to get on with little short stumpy legs )
Another general rule I heard is that your heels should be level with or just below the edge of the horse's belly when mounted. So it depends on both the height and width of the horse. I'm 5'3'' and I'm comfortable with a 14.2h pony. Skinny horses need to be a bit bigger.
I can ride any height and feel ok as long as my saddle is used. My stirrups are set perfectly for my super short legs. And even if the stirrups on another saddle are adjusted I just don't feel secure.
Also getting on a tall horse is getting to be quite a chore for me so my preference has been shorter horses lately.