Fears of bad form

Hello everyone!

I'm Jay, 26 from Germany and I am pretty much baby-stepsing myself into working out and there's one thing that keeps nagging at me.

I don't work out at a gym since I live in the boonies and don't have a car at present so I am stuck with exercising at home. The problem of exercising at home and alone though is that I am constantly worried about bad form.

When I'm doing stretches or workouts and it's explained to e.g. keep the back straight, keep the chest perpendicular to the ground or to not tilt the body forward and I can't shake off this nervous feeling of "Am I actually doing that? I can't tell." Even worse I don't have a mirror in my room that I could maybe use to check myself. (if thats even a viable strategy)

Does that happen to any of you? Does anyone have any recommendations on how to build up good form and confidence in execution?

With regards,