If your form is sketchy, work on form. Drill good form. Example: I found the form that I need to use for conventional that I can really pull with speed but I don't practice my form enough so when I get towards my heaviest pulls I revert back to the 'not so great' form just not letting me get enough leverage.
I would highly recommend drilling your form, finding your weaknesses and working on them from there. Everything from where the bar is placed over your feet, to how you hold the bar, where you drop hips, if you have shoulders over/behind/in front of bar.. it all makes a difference. I can tell when I pull with the right form or not. Both forms I have good back, but one I'm driving up over my toes, causing loss of leverage (think almost SDL) or the other time I sit back, pull and it comes up pretty fast.
Videos would definitely be the best way to see where your form is breaking down.