If i have <0.5g of fibrinogen per l of blood, am i more likely to bleed to death from a 1cm deep cut? could i bleed to death from a long shallow cut?

How do you FEEL?: If this is well below reference range, but you have not manifested any obvious bleeding tendency by age 16, it's time to get with the lab and figure what's going on with the assay. You may have a variant that's not measured by the test, or it may have been consumed on the way to the lab. You're not going to bleed out from trivial trauma. I suggest repeating using a different assay.