here and there people resigning prematurely can artificially boost a person's rating. however you have played about 350 on line games, which is a good size sample size ( my opinion ). and so, I believe your 1700+ on-line Rating is accurate.
I hope you do not get yourself in a rut, by being defensive about your rating. that could result in you not accepting your Rating and gradually sinking to where you believe you belong, a self fulfilling prophecy. Do not let that happen !
I'm sure others have probably written about this. I just wanted to share my thoughts. When I joined chess.com some of my first games were against pretty highly rated players. About half way into a few of the games my opponent resigned or let time run out. My rating went above 1900. I knew that wouldn't hold. My OTB rating has cycled from low 1500's to low 1600's. Here on Chess.com I seem to be hovering in the upper 1600's to lower 1700's. Pretty close. Lately I've had opponents resign when I thought they should play on, and lose on time in very even positions. In one game I think it was the surprise of a Bishop sacrifice. Which if refused would have left me up slightly more than a pawn in material. I hope I'm improving. The OTB rating suffers from a lack of play. I've been able to play once or twice a year is all. So I do think my real playing strength is somewhere between. Maybe upper 1600's. I was wondering if others have a similar experience?