As a 29 yr old with fertility complications for the last 6 1/2 yrs, let me tell you I have THOROUGHLY researched this & ANY sign of pregnancy can also be a sign of PMS. There is no way to know for sure until she's at least close to her date to start her period.
I seriously doubt she'd be having "morning" sickness (I put quotes around it like that because it's really all day sickness) this early, but it has happened before to some, so you really can't tell.
My best guess is to wait one more week & if she hasn't had her period, take a home pregnancy test. They're pretty accurate (I don't have the exact stats). I took 3 preg tests with my daughter ( 9 1/2 yrs ago), they all were positive. When I went to the health clinic to confirm, they didn't have me take one, because the one I took was the same one they used.
In short (too late for that, I know) wait & then test.
How long have you been having sex? If it's not more than a couple of weeks before this started, then she's probably not pg.
If you've been going longer than that & her last period was way different or lighter than usual, there might be concern..... that would put it long enough to have changes & morning sickness, but a test would have confirmed it if she took one.