In terms of actual interviews, if you find them difficult, the key really is to just practice practice practice. Try and practice with any tutors, friends, family etc. Think about your past interviews and think about what you can improve on. Honestly, even faking confidence in an interview helps.
In terms of you general confidence, I think you need to stop thinking negative things like 'I'm ugly' and really try and put yourself out there. I know it's easier said than done, but its good you are self aware about it and can work on it now.