From what I can gather from your shots, I'm assuming that in order to attempt and thwart the low light situation, you opted for a larger aperture to allow more light in. Whilst this does work, it also comes with a shallower depth of field which is not what you're after here considering you have a larger subject.
In this case, you would need to use a smaller aperture to increase depth of field & get more of your shot in focus, increase the shutter speed and bump the ISO setting. Unfortunately, an APS-C sensor is not the best for low light situations.
What I personally would have done is that I would have moved in closer and used an external flash to illuminate the subject so you can freeze the subject better and reduce the need to increase the ISO as much as that will help cut down the noise in your image.
That said, you seem to be headed in the right direction but I would focus more of my attention on composition more than anything else at this stage.