I'm a SAHM to 3 pre-schoolers so I know how hard it can be to keep on top of everything.
do you have a room/area that you can babygate for the toddler? We have a playroom and all toys are in there, I can also shut the toddler twins in there while I get other stuff done. or can you put a gate on their bedroom for them to play for a while?
I work on 'a room a day'. so Monday I wiz round the lounge, Tuesday the bathrooms, Wednesday the bedrooms, Thursday the hallways. kitchen gets wiped down after each meal and swept after breakfast. takes about 15-20mins per room if I do it every week.
I put a load of laundry on when the DC are having breakfast. folding laundry and ironing gets done either when DC are napping or in the evening in front of the tv.
Shopping is mostly online but do a fruit and veg shop once a week, usually first thing Tuesday.
through the day, maybe 3 times I throw a few toys back in boxes to keep the mess level down and then a quick tidy up when DC in bed.
dinner prep is done either in nap time or while dc having their dinner. I'd have your 9yo and 5yo helping with a few chores after school. ds1(4) helps me cook and tidy.
with regard to your DH, this weekend you have somewhere to be, you will be having a lie in and then leaving as soon as you get up, you will not be back until after the kids dinner. leave a list of jobs that need doing while you are gone and a couple of games that you promised he would play with them. it never hurts to remind them how much work just the childcare element of running a house is. last time I did this to DH the house looked like a bombsite! kids were happy as he had prioritised playing with them but never got to the jobs - and has never since made a comment about how much I do or do not do!
give yourself a break, running a house is hard work.