Am I Norwood scale 2 or 3 or somewhere in between? I am 31 (Photo)

It appears as Norwood 3. It would be nice to see pictures of your crown area and to evaluate you for a microscopic evaluation. I would recommend getting a medical evaluation by a hair transplant surgeon not only get a microscopic evaluation to evaluate level of miniaturization but also to discuss medical approach to prevent future hair loss.

From your photos, it appears your hair loss is at an early stage.  If ti concerns you, find a local hair restoration physician to discuss options to maintain your hair and prevent further loss, such as minoxidil (Rogaine), laser therapy (LLLT), platelet-rich plasma (PRP) and finasteride (Propecia), and come up with a plan that works for you

The question to ask is this a Class 3 pattern of balding (early) or a mature hairline. To determine this, I would like to see your frontal view with your eyebrows lifted high so that the creases show. The mature hairline in the middle is one finger breadth above the highest crease and there should be a gentle V shaped hairline from there. See the web reference below