L.,
I'm so sorry for your loss. I have not had an ectopic pregnancy myself but know several ladies who have lost a tube due to ectopic pregnancies and gone on to successfully conceive and carry pregnancies to term afterwards.
If your doc has given your right tube a clean bill of health, I would assume that it is clear as she says and wouldn't think it necessary to put yourself through another procedure. The HSG is not extremely painful but is rather uncomfortable -- I did have one of those. However, if it would ease your mind and your doc will do it, it may be worth it to you.
You might consider asking for a very early ultrasound when you become pregnant again to make sure that the pregnancy is in the uterus where it belongs. Ectopics are a bit more common in IVF patients so some IVF docs make a practice of doing a vaginal u/s early on -- i.e., when the hcg levels top 1,000. While that wouldn't prevent the grief of losing another pregnancy in the unlikely event that an ectopic were again discovered, at least it would give you the peace of mind in knowing that all is well or ensuring that if there were a problem, you were treated before becoming endagered.
Hope that helps,
L.