Does childminder have to wake him up from nap for him to be ready for you?
He's only having about a 10 hour night, sometimes less when he falls asleep later. That's a classically OT child at bedtime. I'd bring bedtime forward to 6 or 6:30 and see if that solves your EW.
I think I'd also cut that bottle out upon waking. At 21 months he doesn't need it, and I have to wonder if he's anxious to wake to have the comforting bottle with mama before she leaves for work.
I might try changing bedtime for 3 days first and then eliminate bottle over the weekend and see what happens! And I'm not anti-bottle -- my son kept his bedtime bottle until age 3, so I'm a late-bottle user too.
If you like the bottle in your lives, I'd just change the time so that it's not associated with waking. I know with BF we often see children waking early for that privilege. I suspect the bottle can be just as enticing, especially if mommy needs to leave for work not too long after.