SHORTER periods??

Okay so I started having unprotected sex the last weekend of April. My period in May was two days with spotting afterwards. My period in June was the same length, only a little shorter. I've had unprotected sex every week since the last weekend of April. Is this a sign my body is starting to work up to a potential pregnancy in the future? Like is my body starting to prepare itself for a future pregnancy? My periods used to be 6 days total. Now only two. Help a girl out because idk what is going on!!!