Frustration!!

Another race weekend, adding to a growing frustration for classic skiing. It seems like all my weekends have started and ended in this same fashion. I'll finish the skate race feeling great, knowing that I skied to my potential. I stay confident that I can do the same the next day with the classic race, and repeatedly tell my self "This is it! This is the day you have your breakthrough classic race!!" This has not happened, and let's just say that my confidence and patience is wearing thin that this will happen.
I realize that a confidence issue is nothing compared to the adversities that some of my other teammates have had to deal with this year, and I'm not making excuses I'm mostly just venting my frustration. I don't feel my frustration to be ill-founded either, because I know that I can do better with classic than I am.
I really don't know what it is, I'll just be skiing in a classic race and I just feel like I'm not going as fast as I can, I KNOW that I am stronger than this!! I KNOW that I can be faster.
I've been trying many things to try to get this irritating monkey off of my back; I've tried different race strategies, different warmups, tempo changes, sleeping more before classic races, much more technique work on specifically classic, etc. The one thing which my sister's, and dad brought to my attention after watching my race today was that my breathing seemed a lot more labored to them today vs. yesterday. I got to thinking about it, and it really was. I've noticed that before as well I just didn't think anything of it and just figured it was all in my head.
So there could be light at the end of my tunnel. Needless to say I'll be a bit embarresed if all of this frustration is being caused by not breathing right. I sure hope that this could be the end of it, so that I can FINALLY be as confident with my classic as my skate.