Again, well done. Those bolts (cool little things) have tips you forged yourself, correct?
A book I recommend is "The Book of the Crossbow" by Ralph Payne-Gallwey, published by Dover. 0-486-28720-3, if you like crossbows. They show one early crossbow, similar to yours, but with a nut made presumable of bone. Still, a self crossbow, but maybe a bit safer? Meaning, the string would be positioned directly behind the bolt (having a bolt come at you would suck big time
But, no more worries about what to make for dinner, I guess).
The illustration shows the guy spanning the weapon by standing with each foot on the bow by the stock. Is that how you draw yours?
Dane