Your going to have to get up earlier!
We can get out in 1h15 (Kids to nursery/breakfast club, me and DH to work, one packed lunch). 1hr 30 is much more relaxed.
Can DS have 2 breakfasts? One before you go out, which ideally is low on the mess factor, and then a second breakfast when you get back?
You've got it right, imo, about food before clothes. Some people will swear by not coming downstairs before everything that needs to be done upstairs has been done.
Can you get up before the kids, and have your shower, then put PJ's or dressing gown on over your underwear?
No playing til you are ready to leave the house.
Pack the bags, and find the clothes, the night before, and put them by the door / on a chair in the bedroom.
Start off by putting realistic times next to all the events that need to happen, add in some contingency for the pooplosion just before you leave, and then work out what time you need to get up.
so, for example:
8.40 arrive at school
8.30 leave house
8.25 start getting coats, shoes bags on
8.20 finish dressing DD
8.00 Mum into shower, hair, clothes etc, DD start getting dressed, DS in Cot to play
7.50 teeth and faces for kids
7.30 breakfast for everyone
7.20 rouse DD
7.00 rouse DS for bf in your bed