Early labor?

Ever since 5 pm yesterday (it’s currently 23 hours later), I’ve been consistently contracting, started at every twelve minutes and has been every three to five since yesterday around 9. I went to the hospital and they checked me, I was 2 cm and 80% effaced. They had me walk around the hospital for an hour to see if my cervix would progress and they would check me again. I didn’t progress, but they had me hooked up to the monitor for an hour and I was in fact contracting consistently every three minutes. They sent me home and told me to come back when I “felt like I was dying”. I’m 40 weeks + 1 day, is this early labor? If you experienced this, how long did it take you until you “felt like you were dying” or gave birth? I’m so uncomfortable and impatient at this point, and really frustrated that I was told to “go in when my contractions were consistently under five minutes for an hour” just to go in at 2 a.m., stay for two hours, and be sent home.