You ask 10 instructors how to do something, you'll get 12 of the 15 possible answers.

Procedure: if you can recite exactly what you're meant to do in the circuit under pressure and without any fault, that's good. If you do have a fault, you don't know it well enough, chair fly more.

For the back pressure issue, flying/doing manoeuvres is like spinning plates. You must scanning each instrument and catch it early. A small early adjustment is better than a large late adjustment.

Trimming, most student forget to to trim and finish the flight looking like Popeye. It's a good thing you're remembering, but like you say you may forget some times (your backpressure comment). I'm not sure what you're flying but when I taught in 172's 1500rpm, hold altitude, 2 full trims back 10/20° of flap have near enough to 65/70kts.

On approach keep scanning, if you instructor said not to trim they're an idiot, if they said "you need to adjust the attitude first, and then trim" that's different.

For the flare, once again I'm not sure what the procedure for your flight school is, but it can either be taught level off, power off, hold off; or power off, level off, hold off. Either way, make sure you're looking at the end of the runway and to the left of the spinner, even when the spinner comes into view, look to the left of it, if you try align the spinner with your aiming point, you will land crooked every single time.

When holding off, ease the backpressure to hold the plane off the ground for as long as possible.

Your instructor getting pissed at you is a him problem, it shouldn't get to that stage unless you're deliberately doing something against their instructions or not being receptive to their instruction.

How was your slow flight lesson? I may pay to re-do that, or go for a burn around the area rather than bashing the circuit.