Not sure if I am official with guy I have been seeing, and am not sure how to ask?

Some general info:

- There is an 11 year age gap between us, causing me to have some confidence issues

- We have been seeing each other for a month, and talking everyday for 2mo

- I am in college and will be returning to school soon, which is 2 hours away from where he lives

This past Friday he met my family and I attended a work event with him, he didn't introduce me as his girlfriend, but it was like "Hey guys! This is the girl I have been talking about". Also, later in the evening at the event, he was openly putting his arm around my waist, holding my hand, and occasionally kissing me on the forehead when we were talking with his coworkers.

Last night we hung out at his house and watched a movie, he teased me about returning to school. We had sex (not the first time), afterwards when we were cuddling in bed, I was going to ask him if we were officially together, but I chickened out. I said instead, "I'm really going to miss this", which he mistook "this" for being the sex and not just being around him, so he made a joke about me having a vibrator to get me by. I texted him saying I would really miss seeing him once I return to school, and he responded saying "Don't worry I will let you bother me through text and snapchat all the time". I told him that I will visit, and he said "good! (:".

Is it okay for me to pose this question through text? Getting the answer soon will relieve my anxiety..

Or should I figure out a way to ask him this weekend (in person)?