I started having contractions from about 30 weeks on and I made it to 38 weeks. Could you have a little stomach bug and that's why you are throwing up? that can also cause contractions. I went into preterm labor at 30 weeks because I was fighting a viral infection. Just keep an eye on your contractions. If you aren't confortable with how they are, you should go into L&D and get checked.
i wasn't dilated either but they couldn't get my contractions to stop so I had a terbultiline shot to stop them. Not trying to freak you out, but even if you are having contractions, you can still make it full term
HUGS to you!