I'd imagine when Shaw decided to leave for Paradise aboard the Engineer ship she'd return to the escape vehicle to salvage whatever supplies she could. As for the lurking menace inside, let's just assume that the Deacon is at least as smart as any other Alien we've seen and figured out how to escape the life boat before she reaches it and she finds the door open. The Deacon has long gone.
Then it's a matter of pillaging anything she finds to take with her on her quest. She (or David) has probably re-purposed whatever has been salvaged to make those drawings.
Why would she even go back to the lifeboat? It's probably the only guaranteed source for drinkable water and food, medical supplies, bedding... whatever. It's worth the risk. Engineer ships don't look to inviting for human habitation. She'd work that out pretty quickly, I'd imagine.
I don't think she ever came back.
We know the creature is "dead" and is kind of a facehugger but Shaw doesn't know that.
Last she saw, she escaped alive with a creature attacking both of them. It could still be here, in fact it could still hunt her.
She knows she can't get back to earth with the Derelict and its cargo, it's way too dangerous.
She makes the only bet she can which is go to the engineer homeworld.
She doesn't need supply, the cryogenic sleep will work well enough and she will have immediate answer upon arrival.
It's likely to fail at 99.9% but that's the only thing she can do and then eventually send it to a distress message explaining everything (why the engineered died and blablabla all the story) just like she did when she left LV-223.