How can I convince my parents I can go out without them kicking me out?

I am 19 years old, almost 20, I go to community college and i still live at home. I have had 2 jobs since i was 14 and am the most responsible person i know. I have always gotten good grades and have been a good kid imo. By the end of my senor year of high school at least half the kids i knew smoked pot regularly and drank and partied a lot. My best friend was always a little crazy and daring so he had a big influence on what i did. We sold a lot of pot and smoked a lot while being completely responsible in life and it never changed any aspect of who we were at home or work. So ive been around a lot and smoked/drank a lot. But as i got older my parents got more and more questioning about what im doing and who im with. Naturally im not gunna say what im doing because im ashamed of it, so i became a consistent liar about what i did. Well this went on til now since junior year in high school til last week when i went to canada with my buddies on a fishing trip, which we stayed ****** up all week while we were there. When i got back, my parents told me they found my bowl and grinder in my room. They were devastated because they felt like they failed as parents by not being nosy enough and controlling me more and yada yada yada. So i get to go to counseling now, which isnt that bad, and if they ever find it in the house again im out, which still isn't that bad cause i was ready to quit anyways (just wasn't as fun anymore and too expensive). but what gets me is because i completely came clean about everything including drinking. Theyre telling me i cant even stay at my buddies house anymore because they obviously know ill be drinking. They said i can wait til im 21 or move out. thats bullshit since ive been drinking since i was 16 and not even nearly as much as most ppl because im responsible and keep a job and ****. So my question is if my parents have no idea what life is like for most 19 year olds, how can i do what i wanna do without being kicked out?