Hi.. Im A Single Woman 30yrs Old , I Make

Hi.. Im a single woman 30yrs old , i make an ultra sound for uterues and ovaries .. Uterus shows normal size .. Left ovary 20*25 mm with leading follicle measuring 19*14 mm ... However when i do blood analysis i found the (AMH) hormone signaled 0.6 , FSH 5.83 mlu/ml , LH 1.22 mlu/ml and prolactin 9.82 ng/ml.. So what it is the cause for decreased AMH hormone ? Pls reply as soon as possible