I lied on my SF86 - Drug use

I’ve been reading a lot of similar stories but just want someone to tell it to me straight based on my situation. Here it is:

One year ago, I applied for a Secret clearance. I had just turned 22. I failed to mention the one and only time I ever did any drugs. I smoked marijuana one night in college when I was 19. I asked a coworker who was in the Army and had a TS about what I should put on my sf86 and she said that the one time wasn’t worth putting on the form. I know, big mistake. I should have found my FSO if I had any questions but asked a coworker instead. Now I know that this minor drug use wouldn’t have caused any issues getting a clearance, but at the time I didn’t. I got my clearance within 3 months, never having spoke to or even met my investigator.

Fast forward: I have had my clearance for a year at this job, but haven’t been actively using it since I never transitioned to a classified site or position. The career path I want requires higher level clearances, but I don’t know how to go about this situation. I fully intend to tell the honest truth if I am ever to fill out another SF86, tell my investigator everything, and tell the truth in a polygraph if need be. My concern is even standing a chance. What do you all think?