Wait am I missing something....
You 'wanted to do it while you are both facing the bed'.....

Is that not doggy style? You are definitely both facing the bed. Or did you mean prone bone.

At any rate, you got at least half of what you wanted, not her fault your cardio capability is non existent. As for the time, you got to fuck for up until 10 minutes time, which I have found (at least on FS shops) they will push you to cum here anyway so you can wrap up and shower etc.

I get the feeling you just came off as untrustworthy, and she was worried she couldn't stop you from taking advantage of the situation if she let you in such a controlling position. I.e do anal without her consent.