In one of your comments, you have said that the social network friend you met is not a virgin. You have not told us how you know. But I do admit from what you have described, the girl seems rather of loose character. It is difficult to believe that a girl will send images of her nipples and boobs so soon after meeting. Are those photos faceless, like I presume yours were which you sent her of your penis?
It was rather foolish of you to ask her on the phone, if she would show you her boobs. This is best done in private when you meet and never play your cards and reveal what you intend doing beforehand. That way you preserve the mystery and can go by the situation and the atmosphere when you are together.
I also feel just grabbing a boob is meaningless and causes pain and embarrassment to a woman. Always begin by holding, cuddling, light neck kissing and kissing if permitted, before you proceed to touching her boobs. I hope you are aware that she also must have something in mind before she allows you access between her legs. So be prepared. Do not become a prey. A few moments of fun and you may repent for the rest of your Life. HIV does not announce itself.
I am interested in knowing what is in your mind for the future. Do you intend carrying this further into a serious relationship or is it only about her boobs?