You are fine. Really all the precautions are for your peace of mind. It the embryo is going to implant, not much you (or your 10lb puppy) can do to stop it.
Oh honey, I am so sorry. To answer your question about losing a twin...yes it is common in IVF to lose one and the other remains and continues to grow just perfectly. Try to relax and take it as easy as possible.
Congrats. Told ya those not so good looking embryos can make babies!! :)
You have to take the test to know for sure. If you are two weeks late a home preg test should be accurate