Oh Jodie, big , congratulations.

You do not sound ungrateful at all, just in shock as we can all understand.
Everyone knows what a great Mother you are and that you will/do love this baby just as much even if it wasn't planned as such. I agree with Jodi that everything happens for a reason, there is a reason that this precious baby has chosen you and one day you will know that reason.

Best of luck for a happy and healthy pregnancy, I too hope that your sisters IVF is successful so you can celebrate together.