Katie
I am so sorry to hear your sad news. Buying a star or angel is a great idea. I have done a few things to remember my angel.
About your question about the Ob visit between 12 and 20 weeks. I think it is 4 week visits until the last2 months and then its weekly. I am not sure as I had various complications during both pregnancies.
The question about heart beat. You can't hear the H/B until about 16 weeks or even later with the moniter they use at the clinics, but you can hear and see it early on a U/S. I seen and heard my angels H/B at 9 weeks on an U/S.
It is great that you have lots of support around you at this time.
Take care
chris