Don't let self consciousness hold you back. Form is something that needs to be learned and a gym is a good place to learn it. Get a session with a trainer to show you what to do and research it online. I've had people say something to me if they reckon my form is off and I've always just appreciated the advice. Mostly people are focused on doing their own thing; even fat people wouldn't be getting ALL the silent judgement they like to cry about. Get your form right and your proteome will improve too.