welcome to HealthcareMagic
Normally the USG of pelvis can pick up pregnancy
as early as 4 weeks so if there is nothing shown in the uterus
i guess you are not pregnant.Still for satisfaction you can get a urine pregnancy test done with first morning sample if you have missed your periods.The follicle on the ovaries in polycystic pattern indicate that you have probably a PCOS
and it is one of the reason to get irregular periods
.So consult a Gynaecologist for opinion and advice.