No guy that I've ever been with who's actually good in bed feels the need to talk themselves up before we do the deed. You mentioning all those positions you want to try was a dead give away that you don't know what you're doing. She probably just gave you a handy because she felt bad or didn't want to seem like she's leading you on.

Also, her friends already know. I would've texted the gc as soon as you walked out the front door.