I apologize for the bluntness of this post, but gosh, don't you have an actual instructor that you have enough faith in to ask these very simple questions, rather than posting them to the internet?
When I see posts like this it really makes wonder what sort of disconnect there is between student and instructor.
It was pretty clear to me that she did, in fact, discuss it with the instructor and that they decided to give it some more work next week.
Perhaps she's looking for additional input. Some people work like that.
As for doing the skill in deep water. That's not very smart on the part of the instructor. This skill is supposed to be learned in shallow water before doing it in deeper water.
..... and now we know why.

me_diver, you've gotten good advice about how to handle the skill. I'll just add to that to not worry about it. There's a reason people need training to learn how to use scuba and the problem you had with getting everything to fall in place is actually not common. Just relax and it will all fall into place.
And go slow. Nothing on scuba should be done quickly. Slow is good. Take your time, think first, then do.
R..