Forgive me if I'm wrong, but that looks smaller than an 18". Where are you measuring from and too? Have a look at On One's website – the sizing guide there (take a look at the geometry tab) to get an idea, but the angle of the seatstays looks too shallow for an 18".
Also, I'd reiterate the need to have the minimum insertion way down the seat tube on such a frame – as you've got a lot of seat tube going above the top tube.
This is a slot dropout 18" Inbred.
To me, it looks like the angles in the rear triangle are different. All four sizes of Inbred share the same head tube length, and as someone else has said, they're designed to run a high rise stem, or low rise stem and a longer fork – but I'd be a bit careful having so many spacers at the front too. The bike looks nice, but the frame looks too small for how you have it set up, IMHO.