Test Results from endovaginal and transabdominal unltrasound

I am a 43 year old pre-menopausal woman who was diagnosed with Stage I breast cancer six months ago.  My tumor was 1.8 centimeters, margins were clear, and there was no lymph node involvement.  I had a lumpectomy, 4 rounds of chemo (I was Her 2 Nu negative).  I chose to have a bi-lateral mastectomy instead of radiation.  My tumor was estrogen/progesterone positive.  I will be starting Tamoxifen therapy soon.  My Obgyn oncologist recommended a vaginal ultrasound as a baseline measure.  I wasn't experiencing any pain.  The test results showed 3 suspected fibroids on my uterus, one being hypoechoic  (1 cm) and the second one being slightly hyperechoic (12 mm) and the third near the fundus (17 mm).  My right ovary contains a 9 mm cyst.  My cervix contains a 6 mm anechoic focus felt to reflect a nabothian cyst.  Should I be concerned with this diagnosis since I've had breast cancer?  Does Tamoxifen increase or reduce the risk of ovarian cancer?  How should I be screened in the future for ovarian cancer?  Is an annual ultrasound sufficient?