I think you are doing a decent job. However when you want to do the same for a big(ger) company, or a bank or multinational like Shell or IBM, the expectations go up. Then your setup will not be enough. I work like you, try to learn, every day. I'm not a professional sysadmin and I don't think I would get a job when I applied for one, but by lack of the real thing, I'm doing the sysadmin job.