Well, if you in particular are being told those two things over and over again, it might be a good idea for you to warm her back door up a bit first with a toy.
I might be worth your while to stop at a shop and get a plug to stretch her out a bit and play with her so it's not quite so intense upon your entering. Make sure it's still in the package. (Or ask her if she has one already she prefers to use)
As far as trying to go balls deep with greek, not all girls can handle it. And those that can, have to let you work your way up to it. Hell, sometimes I need a drink or two to be able to handle it like that with an average sized guy, but I also enjoy getting a challenge. Bring vodka and sprite. Or some fireball chilled.