The movie really jumped the shark when she cut the alien out of herself and walked around the rest of the time like nothing happened.
She was NOT walking around like nothing happened, she was staggering and clutching her belly and popping one painkiller after another. She barely made it back into her spacesuit. When the shit hit the fan, she was going on adrenalin, the painkillers and sheer willpower. No idea how long she was lying there after the ship crashed (obviously long enough for her suit air to almost run out, so we'll say a few hours). No doubt once she and David took off in the other Jockey vessel, she would have had to put David back together enough for him to pilot the ship and put her in cryosleep, because she wouldn't survive the trip otherwise.
There are a few things that irked me, such as Shaw not being as upset about David putting an alien inside her as she should've been, but the general chaotic nature of the ending did excuse the questionable plot points somewhat.
"I guess it's because I'm a human being, and you're just a robot." She likely figured it was Weyland prodding David to do his experiments (or David explained it to her in a deleted scene). David, being "just a robot," was just following his master's orders and bore no personal responsibility. Bit of the same condescending attitude Holloway showed him, when you think about it.