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.