Symptoms at 4dpo??

Just wondered whether anyone has experienced symptoms at 4dpo? I have read that implantation doesn’t happen until 6-12 days, so I’m wondering if it’s even possible that my boobs are sore? I am not ttc, I missed 4 pills out of my packet and then had intercourse a few days later so I’m trying to prepare myself for whatever the situation ends up. I just feel very similar to my previous pregnancy x