Is it possible?

The last few days have been weird, I have been exhausted all day at work and unable to sleep at night. My breasts are not overly tender but feel super full (even my SO was surprised when he touched them by how big they felt), today I had a brown creamy discharge and for one wipe had blood streaks in what looked like ewcm. The rest of the day has been back and forth between milky looking discharge and brown creamy discharge. Could this be implantation? My SO and I have been having unprotected sex and I'm not on birth control but we use the withdrawal method. You can see the pic for how often we have had sex.