Awwww.... it happens. Don't beat yourself up about the shot-- lots going on today, and you've been burning the candle at both ends a lot taking care of Salem. Give yourself a break.
So, if I understand correctly, he got a partial shot (1U) at what would have been his usual +4 (so, +16 from the last shot), and then the full shot (1.75U) at his usual PMPS, which is basicaly +8 from his last shot. This means that there could be some substantial overlap in shot action between this morning and tonight, so it's a good thing you're monitoring closely early.
Definitely a tough situation with the DKA in the mix, I think it was good to have given some insulin this morning, and the fact that it was a reduced shot will lessen the risk tonight dealing with the overlap in shots. So, that part of it was a good call on your part!
That said, giving the PM shot after only 8 hours was obviously not ideal-- next time, I think it would be better to delay it to better match the morning shot (even though it's a pain to have to get back on schedule). Luckily, again, you're monitoring him closely tonight, so if there are any problems, you'll be on top of things to keep him safe.
Post any time you have a question about stuff like this-- even though it's a holiday, you won't be bothering anyone who is on, that's why those of us who are on are checking in! It just may take a lot longer than usual to get answers to your questions, that's all.
Salem's seeing a lot of good greens on the 1.75 dose, he's looking great!