My earlier reply was a little premature, sorry guys.
It is clear that you have fallen in love with this horse regardless of whether it is the same horse in the picture you were given or not, and I say you go for it. My biggest piece of advice is GET A VET CHECK!!!! It is obvious that the seller is not honest, or maybe she just has soooooo many horses that she can't keep them all straight. Anyway, you want to make sure that your beloved is SOUND and that he is the age you were told he is, or an age that is appropriate to you. Don't let people scare you about his age, I have ridden some 3 and 4 year old with more brains and experience than some 14 and 15 year olds. On the other hand I showed a horse who was 25 and consistently received high point or reserve high point.
I also suggest that you not ride alone, at least for a while until you know what his realm of knowledge is. Also, consider boarding at a stable, at least for a few months. My reason for suggesting this is that at a stable you will more than likely find another horse person willing to ride with you and you will be surround by other horse people of all levels who more than likely will be happy to answer questions and help you. I know I wouldn't be where I am today if it wasn't for growing up with my horses in stables where I could learn from other people....not just their knowledge, but I also learned from seeing their mistakes.
Good luck and HAVE FUN :)