This is just some explanation of a small part of what happened to Bella between the post-nurse parking lot scene part one and the post nurse parking lot scene part two. Also a bit on what she's thinking afterwards.
I'm thinking that she's decided to go through Twilight just to prove to herself that she can, and because unlike actual Bella she has made friends there, but whenever it gets to be too much she'd go off for a vacation elsewhere. In her truck.
You see she thought she lost her truck and it was very sad, and then she was in a museum in the distant future. And suddenly it was a case of:
*Runs over to it*
Bella: It is you. I thought I lost you.
Museum worker: You can't touch the exhibits.
Bella: Have you been waiting all this time?
*Bella gets into the truck*
Bella: I missed you so much and-
Bella: Huh? *looks* There shouldn't be a panel here.
Museum Worker: Miss, I have to ask you to get out of the exhibit.
*Bella is now upside down, examining the floor*
Bella: What's under this?
*Bella pulls on the panel*
Museum Worker: You can't do that! Security is on its way already so please make it easy on yourself and-
Museum Worker and Bella in unison as Bella discovers an impossibly large cavity under the floor panel: What the hell?
*Bella disappears in the hole, then pops her head back up*
Bella: I'll just be a minute.
*Bella pulls the panel back into place over the hole, and a locking sound is heard*
*Security arrives, the Museum Worker doesn't even attempt to explain what happened, pretends Bella ran away*
Inside the truck.
*Bella walks around a maze of passageways and chambers.*
Bella: You have changed my friend.
*Comes to a control room, a familiar style of hexagonal console made out of the same rusted metal as her truck*
Bella: I like it.
*checks the readouts on the controls*
Bella: Is this because of the coral I left in the glove compartment, by any chance?
Because ... why not? I have no justification for making Bella's truck into a Tardis other than:
1 She's not going to want to travel space and time without her truck.
2 I think it would be cool.
3 Nothing else.