Am I in labour?

Last week i had mucus plug and little bit of bloody show.

During checkup yesteday afternoon my obgyn told me i m dilated close to 2cm

Since yesterday late afternoon (3pm) till late night (12pm) i have been feeling pressure in my lower back and buttocks.

Now (at 3am in morning) i can feel these lower back and buttock pressure (slightly painful) and i tried to measure the time n frequency. They are slightly irregular in frequency but time 40-45 seconds every 5-7 mins. I m getting uncomfortable and in pain. Can not sleep.

Should i call my Obgyn? What do i do? Do i wait for strong contractions and then call Ob or i should just call?

Any comments or suggestions would be very helpful.