It sounds like you have your max set too high. Especially when you start actually working on good form, your weight is going to go to shit for a little while. You need to make some priorities. For example, you said number 1 is form. Thats good. It can’t be #1-Form and max weight, especially if your form sucked before you started working on it.
I personally feel that anything over 3 reps just burns you out on the deadlift, but thats just me. I have done sets of 10 on deadlift, but the weeks following that myt deadlift sucks. I feel the deadlift may be one of the few movements that actually more reps aren’t necessary.