I advise you to get an ultrasound of the pelvis done. Also, there are chances that lack estrogen, a hormone necessary to regulate your menstrual cycle. To rule out your risk of various health conditions you are advised to consult a doctor. The following tests may be carried out to know the exact cause.
Blood Tests: Most of the common cause for this less flow can be detected by blood tests. Tests for the level of hormones such as a follicle-stimulating hormone, luteinizing hormone, estrogen, prolactin, insulin are important. In polycystic ovarian syndrome, there will be high levels of insulin and androgens.
Ultrasonogram: An ultrasonogram can tell you the thickness of the endometrium, size of the ovaries growth of follicles, ovulation and other abnormalities.
Other tests: Tests such as dilation and curettage and MRI scans are sometimes needed to determine the cause of scanty blood flow during the periods.
You are advised to consult a gynaecologist and get the needed advise and follow as advised. There is no serious problem with this and there may not be any future complications.