Feel like absolute s**t, help please

so basically i just completed my a levels in two years
I've got ACE in chemistry biology and psychology respectively. I really really really want to do dentistry but I'm seriously doubting myself after this shambles of a results day. my plan now is to do a gap year whilst preparing for my UKCAT and getting a **** tonne of work experience/voluntary work under my belt. I'm also going to retake some modules from biology and bump that grade up to an A, retake one for chemistry and hopefully boost that to and A* but psychology. i got 2 u's in both my A2 exams for psych, i honestly struggle with it so much i can not stand it anymore but as I've done it up to A2 now i have no choice but to re do it and better my grade, what are my chances of getting into dentistry for 2017? any advice or something to make me feel less *****ier than i already do would be great.