Pelvic ultrasound (trans-veg.)shows-acutely anteverted smallish uterus-47X32X46 mm. Right ovary looks endometriotic& a haemorrhagic cyst18mm-is it bad?

See your provider. This sounds like a normal size uterus and normal size ovary. Endometriomas are ovarian cysts which contain old blood in them. 18 mm is pretty small. If you haven't had it, you might still benefit from a laparoscopy to look for and treat endometriosis especially if you have 4 years of infertility. You might also need reproductive endocrinologist (infertility specialist) if you haven't already.