Slipping On Slipped Stitches

The summer of 2015 is supposed to see me knitting three, long-queued garments.  My Valentine, probably the easiest, is finished.  Always start with the easy and work your way up to the difficult - that's my motto.

Second on the list is this vest, knit in a slipped-stitch pattern.

 

I think it must have jumped my self-imposed, easiest-first queue  because for being only in secon place, it sure has me discombobulated.    Despite the relatively simple,  slipped-stitch pattern, the construction is confusing.  What could be a very easy knit  - if the designer had  chosen to knit two fronts and a back -  is complicated by knitting, mid back to mid front.  Add to that her decision to mitre the corners and somehow accomodate armholes and whew!  I'm confused.  

Further complicating all of this is  the pattern's lack of numbers.  According to the rows already knit, I am ready to start the armhole shaping. But nowhere does it tell me how many inches of knitting I should have at this point.  Is this how much vest I should have before starting the armholes?

 I have no idea.  In fact I don't even know if I am knitting top down or bottom up or middle out.  (The last one, I think.)  Would it have hurt to tell the knitter this?

At this point in my knitting, it's a guess.   So--- guess I'll keep  on knitting and see what happens.  If I can't make it work out, I'll revert to a two fronts and a back version most designers would have used.