I suggest investing in comfy pants
I look at the pants I wore right before my retrieval in Dec. and I am like Holy Cow!!

they are sooo much bigger than my normal pants, but DEF worth having.
Also, if it hasn't started already, it will start the day of retrieval, you will be peeing like every 10 mins. and it's not like oh I should head to the bathroom soon, it's like you have to stop the car now or I will be peeing in it!
Good news though, the aching ovaries stops pretty much right after retrieval.