Hi Meredith,
Wanting more children doesn't make you ungrateful for the ones you have - regardless of how they were conceived.
We have 2 conceived via IVF and have 2 embryos in the freezeer, so we will most likely go again. I tell myself now that by then I'll be pushing 37, and that will be that - if it works, great, if not.... but I may well feel differently if it comes to it.

I guess you have to balance your heart against your head a bit, especially once money becomes an issue. I hope that little embryo works out for you