Dealing with mesh parts and normal maps

I'm trying to import a model into my scene, it isn't that high-poly (a hair under 45k polys) but apparently too high for Unity to deal with, so it gets split into 2 parts. Thus when I try to apply the normal map I have of the whole model, it doesn't work right. I also assume this will create issues with rigging and animation down the line. Is there any way to deal with this, or do I have to make sure my models are under a certain polycount to be able to use them? According to the console it seems like I have to keep the model under 65k verts, which I believe is around 16k quads, which is pretty restrictive for a high quality full body model.

 

It's 65k triangles, not verts. I suspect your 45k poly hair is quads making it 90k triangles.

 

Ah, I see. Thanks for the info. I managed to reduce the poly count further and import it as a single model, but now I'm getting a "Group1 has no normals, recalculating normals error" and my normal map isn't having any effect when applied. I'll admit I'm not all that technically-minded in this sort of stuff, but seeing as I was able to generate a normal map from my model, doesn't that imply that it has normals? Any ideas how to deal with this issue? Thanks for the speed reply by the way.