Based on my genetics testing, it appears I have two MTHFR polymorphisms. So does this mean that even with all of the proper supplementation, my ability to methylate is compromised?

No. Your ability to methylate won’t be compromised if you take all of the proper supplements. 

Once you correct the cellular deficiencies, you won’t have any issues with methylation.

Once your body is producing an adequate amount of Flavin Adenine Dinucleotide and Flavin Mononucleotide, the MTHFR enzyme starts working again.

But the more mutations you have, the higher the amount of Flavin Adenine Dinucleotide and Flavin Mononucleotide you'll need for MTHFR activity.

And so you'll simply need more Flavin Adenine Dinucleotide and Flavin Mononucleotide to get methylation going.