Size wise I think you're fine to put them together. Putting animals that are used to being alone is a risk so keep that in mind. You have to put her in his cage and watch them full time for at least an hour or two. He will probably circle, tilt and flatten his body and eventually bite the back of her head on the ridge or below on the loose skin and spines. He will flatten her to the substrate and she will flap her arms like he is killing her. This is normal don't stop him.
If he attackes her from behind that's OK. Attacks by either dragon from the front is not a good thing but she may race at him and just bump him with her nose that's OK. She'll do this especially if he ignores her. All this may be scary for you if you haven't seen it before. Keep in mind that if you decide she's had enough and remove her you are only teaching him how to defend his territory as it is not mating season. I would only remove her if she is in obvious distress, stops eating, or is bleeding on the back of her head from his displays.
You could wait another month or so. He will start to get sleepy as brumation season approaches and then introduce her.