Yeah, I think I know what you're going through.
No matter how much you try, they never get satisfied, do they?
Just try and ignore them. After all, it's your life, and if you are satisfied with your score, then that's what's really worth it.
They are sometimes really difficult to deal with but don't let them inside your head. After all, you did good (really great, actually)and that's what matters. Never think that you should try harder (studying 6 hrs a day is already intense, if you study more otherwise you'll wreak your health!) and don't think there is something wrong with you for not getting that 50 (I used to blame myself so hard in the past for bad marks. Yeah, sometimes I deserved it but definitely not in your case). After all, getting 49 or 50 is just a matter of a little chance (at least, that's what I heard, anyway)
Just don't let them inside your head. Try not get stressed.
And take care; studying too much sometimes does my head in. lol