But that's not how the force works!
Who says she can only do certain things? One of the the hallmarks of learning to use the force is just learning to use the force. She clearly shows a talent at learning and understanding things in a concise logical manner. She merely applied that to the force. She learned to resist Ren and get into his head, then applied that to the guard. She did the same fighting Ren again. She's having a problem fighting Ren and uses the force to eke out a win. All you are doing is applying some random metric for jedi power, which is a PT way of looking at it.
Keep in mind it wasn't only the wound holding Ren back, he just killed his father. He hits that wound to stay angry, highlighting a weakness rarely touched on in the darkside, which is it really requires intense emotions to maintain that power. You need to be 100% a total dick to be powerful. Ren was phoning it in. He was conflicted even before killing Han. Then there's the fact the force bully is facing another force user.