These PCA's have to do with autosomal DNA, not mtDNA. Your mtDNA is a very small percentage of your total genetic make-up, even if it may have important effects on health, etc. Therefore, it may, depending on the circumstances, have very little, in fact, to tell you about your total autosomal make-up.
In addition, PCA's in general, given that they show only two dimensions, and capture less than half your autosomal variation, should only, in my opinion, be one tool for analyzing one's genetic relationship to other people.
Also, this doesn't at all say you're from the Marche or, for goodness sakes, the Tyrol. What it does say is that your unique genetic signature, while it is definitely plotting in northern Italy as one would expect, is being pulled east of where one might expect you to be given that you say that most of your genetic ancestry is from northwestern Italy, unless that is incorrect? Take a look at the ancestry of all of your great grandparents and see what percentage is attributable to the Veneto. Of course, given the mysteries of recombination, the genetic signature doesn't always neatly match geographic percentages. Even siblings, through random inheritance, can plot somewhat differently