Match for Match - creating a piece without a pattern

As you may know, I'm making bubba Joe a crochet dressing gown.... and I'm not using a pattern.
I have been using a fabric jacket (purchased)  as a pattern which I will use as a guide & make bigger & longer.
The above photo is what it looks like so far.
The photo's below show the jacket I'm using next to what I'm crocheting.  I still need to crochet extra length onto the dressing gown, this will be done soon (I hope!).

The jacket is in need of iron but it has been stuffed into my crochet bag for weeks now so hence the wrinkles... and besides bubba Joe doesn't mind a few wrinkles.