Cautiously Optimistic

I think I'm getting really tired of hearing that...
We received our results from our frozen IVF cycle and we have a positive...however our hcg level is quite low. They like to see this level above 50 and ours came back at 20. My RE said that he has seen this number come back a little lower with frozen transfers than with fresh cycles. He advised us to be cautiously optimistic. I don't know how to do that with this type of situation...Yay, we're maybe pregnant! I guess I just need to be happy that there's still a level of hope and that our hope today was not squelched with a negative result. :)
My sister said (Cassie), "well, last time you had a great number and that didn't end how you wanted it to, so you'll just have to see what this leads to." And I had to stop and wonder if I'd gotten ANY number, would I be happy with it or would I still feel like I had to take it a day at a time. Yes, I think I would still feel scared and unsure of celebrating too much. So...here's to a postitive test today! :)
I go back on Monday to see if my levels have risen as they should be. I'll let you know how that turns out. :)
Thanks again for all of your prayers, thoughts, encouragement, support and love. We couldn't do this without you all. :)