He continues pushing forward. He manages to slip his hands in, and pushes his feet off the frame. The rest of his arms get in with him, and he's down to his waist.
He ends up somewhat spooked when Sarah tossed around in her sleep, and froze for a second. "Phew, she didn't wake up. I can do this!" He had a bit of trouble, as she flipped around, but eventually he found the frame again.
Sarah started to moan again as he pushed forwards. He can feel the nipple moving slightly, and her hand brushes against his cock. "She must be playing with herself.. Am I arousing her?" With what he could feel, she seemed to be rubbing her nipples, and in turn accidentally rubbed his cock once he got a bit further in.
Trying not to dwell on that, he pushed forwards even more, despite how he liked her toying with his privates. He crawled further, and his legs were the only things out. She was still rubbing, and he could feel each one.
He eventually got his entire body into her milk-filled nipple, and continued through the duct he was in, eventually finding the milk-filled ending. He managed to get himself comfortable, although he had no idea how it was on her end...