Yea It's pretty normal to struggle with clutch & gears for a good while...
But to be glib, what instructor and random lady are saying is right, you need to calm down and take a few mental steps back about gear shifts. The clutch requires finesse, not quick jerks and the same for the shifter, your gear selections need to be confident and firm, not a desperate wrestle. None of these components respond well to reckless movements and all it will do is stress the rest of your driving tasks.
If your car starts to kangeroo or grind, be ready on the brake and depress the clutch again to separate the engine from the transmission until you work out what you did wrong and try again. Clutch control deffo is a skill that takes time... but being able to stop the car jumping and grinding should be a priority... it's easy to say instructors have insurance and should be professional, but I'd expect them still to fume a bit inside at their car doing that repeatedly.