36yo 15mm endometrium at secretory phase. all associated organs normal. developed light spotting during ovulation and heavy periods. concern?

15 mm endometrium: At 36, the ovaries require more stimulation to produce eggs, which in turn increases estrogen production, thickening the lining of the uterus. At "15 mm", this degree of "thickening" requires an endometrial biopsy, as your "heavy periods" may not be always b/c of ovulation, and excessive thickening can develop. See your gyn provider for additional testing .