1. I haven't seen your photography. While it's possible you need to get better or improve your skills, I highly doubt that's the issue. You're not shooting your second wedding. You've got a number of shoots including working with other pros and done it for multiple weddings over 2 years. It's not that you can't improve, it's that I doubt that your skill is the primary issue here.
2. I've been a serious shooter for 43 years now. I have only shot weddings for good friends and not as the primary photographer...it was basically my gift to them. I am very experienced and I can tell you that I'm not cut out to shoot weddings as a primary business. A professional wedding photographer will tell you that while there is skill involved, the most critical pieces/competencies involve dealing with the brides and mother-in-laws. It's a unique skill set for a photographer and most of us aren't cut out for it OR even if we could do it, wouldn't enjoy it and would come to hate our art.
It sounds to me like it's not the photography issue, it's the client "dealing with a wedding" issue that's the big factor. Yeah, you sometimes have bad days. Yeah, you're honest enough to realize you don't always bring your "A" game or could improve. But it doesn't sound like those are the primary issues. It sounds like you still love photography but you just don't really enjoy the elements that go with shooting weddings...the organization, the client interaction, managing the expectations, dealing with people trying to get a bargain and expecting a gazillion edits, people making copies and cheating you out of income...all of the stuff that is part of being a wedding photographer.
If you can afford it financially, I suggest you walk away. You should enjoy your photography, not come to dread events you're shooting. I know a fair amount about shooting weddings--more than enough to know that I'd do terribly as a wedding photographer with that as my primary business. I'd start to piss off clients, I'd come to hate my camera and despise my art. The wedding photographers I know are very good photographers but they're outstanding and dealing with all the stuff that goes with shooting a wedding besides the shooting. Which is why I know I'd be no good at it and it sounds like you're the same way.
As to the post from the bride-to-be about not walking out, I think you have references you can give them. And what couple wants to know that they were your last client before you quit shooting b/c you didn't like doing weddings? Ugh. You want to deliver a good performance for the couples you're scheduled to shoot. And if you have started to hate doing this (shooting weddings) or at least dread it, then it's a mistake to stay with those gigs.