Why else would I have pelvic pain/fullness?

I don’t think I am pregnant this cycle, based on lack of symptoms, but the only thing I have and have had since 6dpo (I’m now 9dpo) is a pulling and I’ll feeling in my pelvic area? Lower then where I would have period cramps. I had this when I got pregnant the first time, but also had sore boobs at 8dpo and I’ve had nothing.