So I've been on grad admissions at a selective graduate program. A different field but some of the concerns you mention are really similar. Your concerns are l

So I've been on grad admissions at a selective graduate program. A different field but some of the concerns you mention are really similar. Your concerns are legitimate but people do get into programs and continue on. You're not the only one who was young and made mistakes. People at good programs know this. (They might argue about the significance of it but usually there's someone level-headed around to put a dose of reality in the conversation.) Generally speaking the way I see students with regrets get in to programs later is to build up evidence of their skills and abilities, and then find someone to advocate for them. That is, they take more classes and ace them, or get good standardized test scores, volunteer on research projects for awhile, and so forth and so on, and get someone "on their side" on the admissions committee who can vouch for you. I don't mean anything nefarious, I just mean things like, if you volunteer on a research program, there are people involved in that research program who will know people or appeal to people (intellectually/academically) on the committee, or might be on the committee themselves, and they will be more receptive to you than if you were just a complete stranger with letters of recommendation from people that no one knows anything about (which is why program fit is important, among other things). Your background in the "real world" is pretty compelling, you just need take that and other things to build up evidence to make a case. Think of it as like a legal argument and you're making one for why you should get in. Be honest about your mistakes when asked about what was going on, but don't include it in statements or anything like that. Or if you do, spin it in a positive growth-oriented way. You might also want to be really creative with the types of graduate programs you consider and why. I don't mean that as a euphemism for "seek around for whatever program can take you through the back door", I mean think carefully about where you are in life, and where your strengths are, and what types of programs would get you the furthest along from A to B, at least as you can see B at the current time.