If you feel comfortable moving up to a 125 I say go for it. My son rides my 125 and he is only 5'2". He couldn't race it but rides it all the time. With that said, don't move up unless you really are comfortable with the size. He is not and I will be getting him an 80, YZ probably.
The problem will be when you drop it. Can you pick it up, hop on, and restart in a reasonable time with other bikes zooming past.
If you decide on a 125, as much as I like my Husqvarna, and even with the fact that for a 125 it has a lot of low end that makes it eaiser to ride, I would not reccommend it to anyone under 5'7". It is over 38in at the seat.
At 14 you still have a year left to race, 80cc mini class off road and MX, or 100 cc Boy racer class for MX.