I think it is great that your RE is encouraging, as that is a hurdle for lots of women on these boards. Below is a link to my story, which is similar to yours. I agonized over the fact that if I ever had another child, my kids would be too far apart, but it hasn't mattered at all in the end, and they are almost 5 years apart.
Best wishes to you, and I hope you find some hope here. Let me know if you have questions.
(This board is very slow, by the way, so you may want to visit the "new high FSH" board, just be sure to be sensitive in your messages of the fact that you have a child already and many there don't.)