I'm thinking maybe I'd need to see a pic of you with a middle part, BUT since you have a heartshaped face - your best bet is a side part. So you can part it on the other side, but you'll look best with a middle part.
Try yourself, take pics and compare. Or even better, go to a good hairdresser and ask him to restyle your hair. Very often they have computer programs where they can simulate so you can see the result in advance.