I Sympathise with you 100%. You know what? Your friends will understand why you say you can't attend.
You don't have to go. Its the most difficult thing to do if you are ttcing.
Think seriously about not going because if you go it will upset you.
There is no guilt in not going to these showers.
You have a shower of your own when the time comes and invite all your friends and give each a bottle of champagne to take away, best, THK