Possibly going in to labor at 34 weeks!?

So I have had issues with preterm labor since 25 weeks which was so scary to constantly have contractions not knowing if you will start dilating and go in to labor. Well today I had my growth scan and found out she’s measuring big! They said they can give me medicine to stop the contractions until 34 weeks but after that if I go in to labor they won’t try to stop it. Meaning I could possibly have my baby with in 3 weeks 😅 any body ever heard of this before? I thought they wanted you to go to at least 36 weeks?