thanks for using health care magic.
Your past gyneco-obstetrical history is very relevant and could explain the reason why you have not been able to conceive recently.
If you were operated during your last two ectopic pregnancies and during each surgery the ectopic pregnancy
was in a tube and it was cut out together with the tube, then your tubes are no longer patent and sperm cannot reach the egg for fertilization.
A common cause of ectopic pregnancy is a chronic infection in your pelvis which can also cause fluid or pus to accumulate in the tubes thereby preventing sperms from reaching the egg.
Given your history, these are the most likely causes that have to be ruled out before looking at other possible causes.
What you should do is to re visit the report of the management of your ectopic pregnancies and if the managment was conservative ( medical treatment or by endoscopy
) you should get an ultrasoud and a hysterosalpingography
tests to evaluate for chronic infection and patency of your tubes.
Best regards and hope this helps you.