Pieces of me

I have never been terribly good at organising my appointments (unless they are doctor's appointments in which case I outline them in red on a calendar). When it comes to social occasions, it is not uncommon to find out on the day that I have unwittingly agreed to be at several places at once. Call it spontaneity; eagerness to hang out and party at any party; it is thus difficult enough to catch up with my own self, but now I have a doppelganger in the form of M. it is becoming troublesome and a source of tension.
"Do you want to have dinner?" a friend asks, and I usually just agree.
"Don't we have to do X, Y and Z?" a bewildered M. asks, later on in the afternoon, and then I realise that we do. But I'd also agreed to have dinner with my friend.
"Do you want to meet up on Saturday?" a friend asks, and I say yes.
"Didn't you want to do X, Y and Z?" a rather cross M. asks, on a Friday evening, and then I realise that I did. But I'd also agreed to meet up with my friend.

And so it goes on. It has got to the point where M. tried taking pre-emptive action. This is what happened when I told him I was going to meet up with a friend.
Me: "I'm going to have lunch with my friend H."
M.: "OK. DON'T AGREE TO ANY WEEKEND PLANS."
Me: "Oh. All right."
Thus warned, I went off to see H. - and merrily agreed to go to a party with her on Friday. But the warning did have some effect, as on my way back to meet up with M. I suddenly realised what I had done. Sheepishly, I had to confess to him what I'd agreed to. M. just shook his head and said somewhat sharply, "Well, I guess you're going to the party alone, since I'm going to be tired on Friday night." I could have cried. The way I am going, I will be an indolent, inconsiderate wastrel who will never spend any time with her boyfriend she worked so hard to be in the same city with.

I am going to buy a pocket diary, and use it. I will stop saying "Yes" to every invite. This is going to be hard to do, changing the habit of a single girl about town.