On 17th aug i lost my virginity with my partner we had unprotected sex as he did not ejaculated inside me nor his pre-cum. After that i couldn't recollect the date of my periods. I tried too so i guess it's was on 1-4 aug. Now I'm worried i dint get my period yet. Actually all the time i have noticed my menstrual cycle has fluctuate dates it doesn't come on time. So we are in too much stress and worried wether I'm pregnant or what so  please need  suggestions. What is it?? Do i need to do something or this is normal.?