Am I farther along?

I know based of the gestational age (according to my period) I’m currently 26 weeks pregnant. However, I usually get super bad cramps on my period, but the last one I had wasn’t nearly as bad as they usually are. I’ve been getting pregnancy symptoms earlier than I was supposed to as well. For example I could feel my baby kick at 16 weeks, my nipples have been leaking since 23/24 weeks, and in the early ultrasounds my baby is about 1.5-2 weeks ahead in his size (by length and weight).

Are there any moms who experienced this during their first pregnancy? Am I farther along than what doctor says based on gestational age? Should I be prepared to have my baby early? Is he just big?