i'm in a similar position, been playing in bands for over 15 years but never knew any theory to do with scales etc... i always picked things up by listening but never really knew what i was doing. I can't say it's held me back as like i said ive been in multiple bands for over 15 years now but after being a member of guitar tricks for the last 18 months my guitar playing has improved massively and now i'm really starting to understand what i'm playing.