You are going to feel insecure about it that is natural, either is works for you two or doesn't you won't know until it happens, You will either be turned on and so will she or you will be angry and she will feel guilty. Only one way to find out.
i used to see a guy that would fuck me silly but when he was ready to cum would always pull out and put it in my mouth, for some reason he liked me swallowing more than pumping it deep in me. I prefer it in my pussy but when with a bbc it is his choice where the cum goes.