BS means nothing. People would be really amazed how many schools do not require a BS to apply. I know a doc who got in with his 90 hours to a good US school, went on to Urology residency and is now making absolutely phat bank working in private practice.
If you've been accepted, then there's NO reason whatsoever to put it off for a year to finish your BS. Heck, the school might not hold your spot for you, even... why would you apply yet if you're not serious about going? That would be what I would think next year when you re-applied. Just me, though.
I am in my last year of Caribbean med school, have no BS, no degree whatsoever, actually. MD will be my first degree. 😀
As for the people who say you'll regret it later... why? It's not like you can't finish it later if you wanted to, right? I mean, if you're only 2-3 classes short (like me) then it would take no time. If it's a whole year, who cares? I really don't see why you couldn't do it later if medicine didn't work out.
Good luck, and congrats!