Endometrium biopsy under general anaesthesia was done previously to check ovulation but nowadays other easy investigations are available like follicular study and day 21 serum progesterone.
You must have gone through all basic investigations Like follicle studies and Tube testing.;
Thyroid function test ; serum
prolactin ;
FSHLH ; and basic health check up tests.
There are other invasive investigations like Hysterolaparoscopy. If your doctor is asking about Hysterolaparoscopy then go for it. If doctor is asking you about endometrium biopsy as opd procedure without anaesthesia on first day of menses; then that is to check tuberculosis of endometrium. Please check with your doctor the reason for biopsy. If it's for tuberculosis then go for it.