Ours is about the same size, but has two doors, opposite each other - so one door into it, and the other door to the outside. It makes the layout a bit awkward to plan.
But this is what we have in it and it all fits fine:
Washing machine
Tumble dryer
Sink and draining board
Cupboard for cleaning and laundry stuff (I seem to have lots of both
Another big cupboard which has kids paints and brushes, shoe polishes and brushes and cloths, sun cream, first aid basket
On (many) hooks, bags with swim kits, picnic rugs and sports kit bags
Other heavy duty hooks for hanging the ironed things when I'm in the middle of the ironing (rather than me hanging it on the back of doors etc and it all falling down)
Ironing board (the iron is wall mounted)
Three airers
Three (stackable) ironing baskets - one for hangers, one for things to be ironed, one for things which don't need to be ironed and are waiting to be put away
Vacuum cleaner, mop and bucket, dustpan and brush
Wellies - ours are stored upside down on the floor on a stand that is something like this but I would love to have them off the floor.