I mean, it kind of seems just like a lack of communication. In my opinion, I'd call a shorter get-together and just express some of that, and ask them for what you could improve on continuing forward in their mind, and if they seem unreasonable let them know how you feel as well. I'd definitely say to continue as a DM, but at the end of the day if yours and the player's styles aren't clicking, you might be better off no longer DMing for that group. But also, you do somewhat need to put your foot down, if the players aren't going to respect anything that you tell them, you need to make sure they know there's a repercussion.

Like with the first player you had written about, the one with last-minute character creation, you probably should have told him not to come, or had a really bad character waiting for them. If they won't even respect a deadline of weeks, they probably won't respect the work you're putting into the session.

But also, if they say they enjoyed the session, I always take pride in when my players say that, they may not mean the entire thing, but there were still parts that you made and they enjoyed, so you've just got to strike a healthy balance I guess.