Practice makes perfect! If you have friends, family and/or mentors, practice for them and ask for constructive criticism. If you do it 100+ times and it's all positive feedback, there is no reason not to feel confident. I just went through @INcubes accelerator program - probably practiced my pitch 500+ times for over 100 different people. Everyone had little nuggets of advice that I held on to until the presentation was perfect. I'd be happy to take a call, listen to your presentation, provide some feedback and ask a couple questions to ensure your basis are covered.