Talk to Gynecologist on Periods

my periods were expected on 28 march but they didn't come I did a urine test but it was negative then I waited a week more and got a blood test it shows 28 HCG then I got another test one week later it shows 48 HCG and then after 3-4 days I got spotting and the next morning I was bleeding and after an ultrasound it shows nothing there it was 16th April, so then I assumed that my periods will come at 16 may coz I have a 30-31 days cycle but they didn't come. now I'm tensed that is there any problem should I go for a checkup or anything?? my ultrasound was ok there was nothing there everything was normal