Hi, if it makes you feel better, I live in a teeny tiny house too!! (Like 92m2 or something??? I saw an office space for rent the other day, and it has 94m2 - bigger than my house!!) So a teeny tiny 3 bedroom house. We are going to have 3 kids too (just workin on brewing the second one up nicely) so our kids will have to share too.
I think it can be done - i'm worried about lack of space too - cos I LOVE SPACE.. and i hate clutter. So every couple of months, I just make a concerted effort to go through things, throw out things that are broken, donate to charities, etc etc. Try to keep clutter down to a minimum (which is hard cos I'm a hoarder too!!). I love storage boxes, i have them under the beds, in the wardrobe with shoes on top (doubles as a shoe rack!!) so they are all within easy reach if we need them, and if we don't - hidden!!!!!!
I don't remember having a huge house when I was a kid, and there is three of us, so I'm sure if my mum can do it - so can I!!!
So good luck!! I wanted to let you know that you aren't alone - even though I have no real advice for you.... lol... sorry