I guess by being pessimistic, I am just trying to protect myself from being hurt!
It's not working.

You're nervous, obsessing about bad outcomes and you won't be able to sleep tonight. That's actually causing you more pain, not protecting you.
Being pessimistic isn't doing much for you, so try and see what optimism can do! Say, "I can't wait to hear/see my baby's heartbeat for the first time. It will be such a joy." And please post tomorrow! Wishing you the very best.