3-Turn control

During my lessons, I can never seem to control my 3-turns! My upper body keeps on turning, dragging me out of my 3-turn. My coach says it's because I'm not checking, but I swear! I am trying to check as hard as I can, but I still turn anyways! I suspect I don't really understand what checking really means. Does it just mean that you have to keep your arm in front of your body and blocking it from turning? My coach also said something about keeping my shoulders alinged with my hips. I really need help on these 3-turns...my coach is getting kind of fed up.

P.S Is it possible for a coach to fire a student?

Practise on the hockey circle. Keep arms along the tracing but inside the circle at all times.
After pushing off, turn body box to face the inside of the circle. There is a down up down of the skating leg when you do the turn. Keep head facing direction of travel (along the tracing). On the second down when you are exiting the turn, there is a counter motion of arms vs body box (checking). While head still faces backwards along the tracing of the hockey circle, body box turns slightly away from center of circle while arms remain along the tracing but at all times within the circle. The counter force of body box and hips vs arms is the checking.

P.S. You won't be fired. Coach wants to help you! Good luck!

What my coach does when students have problems checking 3-turns, is to hold on to both their hands all the way through the turn, keeping their arms and upper body in the correct position. That way you feel a slight pull in the muscles you need to tense and it can help your body learn what checking should feel like.
It also helped me to imagine I was holding on to a ballet barre. You can practice checking 3-turns off-ice with anything stable like a barre, wall or banister to hold and then move on to doing it off-ice without a wall and then on-ice. Doing some core and upper body workouts might help to strengthen the needed muscles and familiarize yourself with them, too.

What does your coach have you doing with your arms? For example, on a LFO 3-turn, does your coach have you keep your left arm in front from beginning to end or does he have you start with your right arm in front and left arm back, and just turn from the hips down so that your arms stay in the same place and your left arm is in front of you on the 3-turn exit? Both ways are correct, depending on what you're using the 3-turn for. The second way helps prevent over-turning, though, so you might try it if you haven't tried it yet. But if your coach wants you to learn it with the same arm checked in front from beginning to end (that would be the left arm if LFO 3-turn or RFI 3-turn), just try to think of your body as being completely frozen in position like a porcelain ballerina that rotates on top of a music box. Imagine you can only move from the ankle down. That's what the 3-turn should feel like. You'll be amazed at how little movement is actually needed. A coach once told me he mastered this 3-turn setup for his triple salchow by imagining he had a full glass of beer balanced on a tray right over his chest and he had to make sure he didn't spill it.

Thank you guys for the much-needed advice!

@Chump12: Haha my coach also suggested that I practice my 3-turns on the hockey circles... They are getting better. My private lesson is tomorrow, and I hope I can show my coach that I've improved!

If you want to try some off ice techniques, I've found this helpful

http://icedoesntcare.blogspot.com/2015/08/my-knee-bend-3-turn-checking-posture.html