Is it worth trying?

After many years of "mistakes" and not completing what I started I decided I need to go back to school and go back to my original major. RN. Since then I made the mistake of getting charged with a misdeamenor, possession of cannabis. This was 7 years ago and I got a reality check when I had to get this "behavior block" removed by the Dean in order to register. After reading about the RN program and admissions into the health sciences division I am not only disappointed in myself but wondering if it's even worth pursing at this point. I have read many things *(I am a googler ) about how I will have a hard time not only getting in but getting my license also finding a job with stipulations they may put on it. This is a big decision for me and I am scared that I will spend all this time and money only to hit a dead end. At this point I am wondering if expunging my record would be worth it or not. From what I read I'd still have to let them know my charges? I know I probably should speak to a lawyer but I am wondering if anyone can shed some light on this.
I have prerequisites I need to take and I don't want to take all the ones geared towards RN or medical if I am going to HAVE to go a total different way.