Period cramps or pregnancy?


My boyfriend and I have recently decided to try and have a baby. we've been trying for about a month. I deleted this app and when I re downloaded it, I lost my login info to my other account. I wasn't sure when my last period was, but I started ovulating the 9th to around the 15th of December. I remember my highest peak of ovulation was on the 13th (it's our anniversary and we decided to go for it). We have had plenty of sex since then, and each time he has came inside (TMI, sorry!). My period is supposed to start the 28th. The past few days my boobs had gotten pretty sore but they aren't anymore. I have had slight cramps also, and they have been on and off for a week or so. I'm new to this so I'm not exactly sure what all to look for or expect. no rude comments please, just looking for opinions on what it could be and possible adivce! Happy holidays 🎄