Should I be consurnd bout my period?

Ok they all say your period is suppose to come every 28days well recenty I thought I missed my period and I thought there was something wronge because I was really dizzy and tired ... And felt sick ..this last week and today I think I started my period but it's only lil spots well mine came the 38th day does that mean somthing should I be worried.... And last month me and my bf were messin around but he didn't get hard nor ejactulate nor pre so idk wats wronge