I do get the busy mum thing. I have 4dcs and rarely get a minute to myself.
I am neither boasting nor moaning when I say that, but it's the truth.
DH works late shifts so life is pretty full on, our 4 year old no longer naps during the day and doesn't start nursery until September so I don't have any time to myself. I get up at 6.30 with our toddler and then older dcs up for school, and from there until dd4 is in bed at 8.30 I have little spare time. Then from 8.30 till probably 9.30 I'm putting the house straight, dealing with the mountains of laundry and dishes and mess built up through the day.
I totally get the going to the toilet thing - I can't leave youngest toddler alone while I go and she can actually get out of her playpen so safest just to put her in the corridor outside loo with her toys and leave door open, or bring her in with me.
MY bugbear is, I do have time to brush my hair though not always to style it properly. However I never understand mums who seem to completely give up on looking nice when they have kids and start dressing in shapeless fleeces, jeans and those black mum boots. And get their hair cut short like men's. It presumably takes the same amount of time to put on a nice dress and cardigan and leggings which retain some degree of style as it does to put on aforesaid mumiform.
So yes I get the busy thing, I am pretty organised but genuinely don't get much time to myself - only typing this as my mum is round on rare visit giving them a bath! But don't get the 'no time to look nice now I'm a mum' thing.