A DIY high chair for Chupi

We always said we were going to get the Stokke® Tripp Trapp® chair in a bright colour for Chupi once she got big enough...

suddenly she was big enough and we really needed a high chair but I knew it was going to take ages until we got our thumbs out of our a**es and go get her a chair.
So Sunday a week ago I thought I could DIY a high chair instead...and I did.
It took all bloody day but it turned out pretty cool I think (my boyfriend's parents think it looks like something found in an institute for the insane), I mean improvements could still be done now looking back on it but it works and Chupi seems to really like it. 
Judge for yourselves:

You can see in the background how the chair actually looks before covered with the "high chair".

This is what I did:

I placed two square foam pillows on the seat of the chair and covered them in fabric going around the underside of the chair seat and then added push buttons to attach it all the way around.

I covered the backrest of the chair with the same fabric and sewed it onto the pillow part also fastened with push buttons at back.

I sewed the harness part seen in the picture onto the backrest fabric with lots of push buttons to make sure it would fasten securely around her and that I could make it larger as she grew.

I shoved a pillow down the back behind the fabric for back comfort and softness and that was it.

It is easily removable with the snap buttons so it can be machine washed which is necessary as I have already had to wash it twice since making it.

Sounds complicated? It was a little complicated :)  - I didn't have the patience to create a pattern so I just started sewing and I wasn't smart enough to document the progress with pictures, but should anyone be interested I can probably come up with a better description on how to do it including both photographic and hand drawn pictures, just let me know.