My naive questions: about bed rest

My naive questions:
1. How big is the embryo? 120~150 microns... Just guessing... Bottomline microscopic.
2. How big is the opening of my cervix? Is it open or closed? For sure, it must be bigger than the embryo size. Big enough to be seen by a naked eye.
3. Less than 30 minutes after the embryo transfer, I stood up to pee. My big question is why it won't drop?
4. I walked to the taxi stand, what ought to drop must have dropped! Am I insanely having bed rest while the embryo was flush in the toilet already?

Hay! If my naive questions were true, then the new standard for embryo transfer entails one week hospital stay. Every clinic / hospital wants to maintain their high success rate. Since, it is not implemented, ergo, bed rest is not necessary.

I will have my bed rest just to free myself from guilt. Because, I don't want to be labelled as stubborn. Hmm... I have walked few corners because I was craving for dessert last week. Sad to say, my husband cannot imagine what dessert am I craving for. Shhh... Neither do I! Finally, it was mango puree with yougurt. I lost my food craving this week. Ouch! No more pregnancy hormones? Scary.

Can I tell my reproductive immunologist that my food craving is more reliable than his beta hcg request? No kidding, I have food craving whenever I had hcg shots.

I feel bloated this cycle but I still crave for comfort food. I dont care if this is coincidence or psychologic issue. This is my observation as an iui veteran!