Pelvic pressure?

I’m 28 weeks and 2 days and started experiencing pelvic pressure this morning after sitting for awhile. I noticed it as soon as I stood up. I called my doctor’s office and the nurse said that it sounds normal but that if I want to get it checked out then to come in. So I'm going to go in this afternoon but was wondering if any of you have experienced this? Part of me feels like I’m just being a nervous Nelly but I also don’t want to brush it off as nothing because I’ve read (evil Google) that it could be a sign of preterm labor. This is my first pregnancy so I don’t know what is and what’s not normal. Thanks in advance for any responses!