A little worried

Robin • Mommy, 23 yrs old 💞, Married 💕, 💙 Damon Quill born December 6th, 2018 💙, Athena Rose born July 9th, 2020 💕

So has anyone else's doctor already told them their cervix is at 3cm? I looked online and you arent supposed to hit 3cm till around 30 weeks and I'm only just about 20 weeks. I get rechecked on Friday but I'm still nervous since I've never had to have injections or a stitch there with my son. I did go into preterm labor without delivery with my son but it wasn't until 34-35 weeks.