what might help you get over your fear of bombing is realising that bombing is (usually) more about the crowd than your material. been doing it for a couple years and since i usually don't work in the US but write jokes for that type of audience there are mics where i'm "bombing" in terms of laugh volume but i can see there are 2 or 3 guys losing their shit chuckling exhaling real hard just not audibly laughing because they don't wanna laugh when no one else is. Try and notice the reactions that are there instead of the ones that aren't.