I'm 5'5" not much taller than you and I'm 42 years old. I've got nothing but shrinking at this age in life. I'm just now starting out as well. I find that some of the chords are kind of hard as well... We all do. I'd suggest keep going on it. Do your best. Chances are, you may grow some more.
It's going to be difficult, make no mistake about it, not because of your size, rather, learning guitar is difficult. You're mind is telling your hands to do one thing, your hands are telling your mind, "no thank you". But... eventually, your mind wins and your fingers will begin to comply. :D
If after a few months you still are not getting anywhere due to the size of the guitar, maybe you should hit your parents up again for a different guitar.
That's just my 2 cents anyway... I'd expect someone with a lot more experience to chime in and possibly give better advice.
Good luck!
Rick
[U]Ricks Current Mystery Video[/U] - Updated Monday March/02/2015