Thank you, good advice there!
One more thing: please also provide an alt text for your photo, that way, people using screen readers will be able to understand what the photo is about.
I think you are way too hard on yourself and being in the audience of the last speech I can say you did brilliantly despite the technical difficulties. I suspect the previous talks were also much better than your description of it.
I’ve been a teacher to various ages and abilities, and yes….recycling previous presentations…