You've hit on what seems (to me, a newbie) to be one of the hot-button issues of the forum. There is support for both the "wear what you want" school (the entire idea of clan tartans is a victorian invention, a lot of it is absolute balderdash, and highlanders 'back in the day' wore tartan of whatever colors the weaver happened to have on hand) and for the "wear only tartans you have a 'right' to" school (whatever the history, clan tartans have been accepted for a long time now, and so you shouldn't wear a tartan just because you 'like the colors'").

I think the idea of any "right" to a tartan has been pretty well debunked. But it's more a question of taste. And tastes differ. I feel more comfortable wearing a tartan that I have some connection to (even if that is just "well, the band I played for when I bought this kilt wore this tartan"), and if I buy a kilt for my own personal (rather than band) use, I prefer one in a tartan that my ancestors are connected with in some way.

Ultimately, though, you don't need anyone's permission to wear what you like. If you feel more comfortable that way, then I fully support it (I feel the same way!) but suit (no pun intended) yourself.