To those saying he should get a 125, 2 years experience on an XR80 does not prove he is ready for a 125. Especially when no one in his family rides and can help him with what is safe and what isn't. Also, all of the 80s are designed for a rider from 100 to 160lbs. Until someone is over 5'5" 160lbs they aren't TOO BIG for the bike. They may be good enough to move up before that, but that doesn't make them too big for an 80.
My son is 13 5'1" 110lbs and fits his yz85 about the same as I fit my 125. He has riden my 125 but certainly cannot yet handle it on a track.
The real tell is, can you pick it up after you drop it, restart it on flat ground with out something to stand on.
With that said, yes you are too big for an xr80. And you should fit a CR80E or KX100. On the CR you sat on, how far did the bike sink? It should drop about 3 inches with you on it. If it didn't it wasn't set right for your weight. Also show you mom that the shock has an adjustment and you can lower the seat. You may have to adjust it down lower than where it handles the best to get her to let you have it, but once you show her you can handle it, then you can adjust it back up.
Oh and you should have asked her for an XR200, then settled for an CR80 when she thought the XR200 was too big.:debil: