I've written that six slides is what got it done for us.
And the best presenations I've seen lately used no slides, but started with a live demo of a working web app and went from there.
Nothing beats a demo in my book. It allows the founder(s) to talk about what they built, why they built it, and where it is going "in situ."
So think about ditching the pitch deck and using your app as the backdrop for your fundraising meetings. I am confident you'll like the results.