I'm pretty much full grown... I'll be 19 in January. My hands are only slightly larger than my 12 year old sister's. My palms are wider and thicker, and my fingers are a bit thicker too, but my fingers are super short (my middle finger is like 3.25 inches). I have been playing guitar for about 4 years now, and I played piano before I played guitar, so I have been stretching for a long time now. I have no problem stretching from like the 5th fret to the 10th, and I can reach the 11th, but not reliably enough to use it in a passage. I can do an Am9 chord (x, 0, 2, 4, 1, 3), or an Fadd9 (1, 3, 5, 2, 1, 1) which are pretty tough stretches. I rarely feel the need to stretch more than 4 frets anyway. Having small hands is somewhat of a hindrance in the beginning, but it can be overcome by stretching. I can set my palm down and stretch my thumb and pinky just about 180 degrees. Just keep working, and you'll get it.