StrongestMummy I'm glad you found my post helpful, it genuinely was intended to be, and well done for getting your DD into school early 
I said earlier that I used to be late a lot. LIke you I pissed off friends and employers.
Like you, I wanted to change. I think some people do have a sense of entitlement, but that wasn't the (whole) reason for my lateness and it doesn't sound like it is for yours either.
So something that was a turning point for me, might help you - and answer PigeonPair's question as to why it's still hard for you to be on time.
I realised that my lateness was a form of self-destructiveness. I can't say exactly why I was doing it, but I was sabotaging myself. It's not fun to piss friends and employers off, and I remember a couple of bad bollockings 
So I when I started to look at my lateness in that way, with some self awareness, I was able to sort of monitor myself. So for example, in the morning I sometimes want to sit and play on my phone - "only for a few minutes" instead of getting ready. I will talk to myself and say 'why are you procrastinating when you know rationally that if you don't get your arse moving, you'll be late? Why are you purposefully wasting time you don't have, or pushing the boundaries and leaving things to the last minute? You know that if you're late, then DD will be late, and she'll feel embarrassed and maybe get told off, and she'll feel bad, and then you'll feel bad. Why are you doing something that will lead to you feeling bad about yourself?"
Now, I never have the answers to those questions, but that self awareness is enough to get me moving. Like a sulky teenager, mind you, but at least moving!