Being told "not to stress about it" by Coworkers

I'm looking for advice to best handle a constant and reoccurring problem at work with one of my coworkers.

My husband and I have been TTC for over 3 years now and after late AF visits I just can't get my hopes up anymore because every time I do I get emotionally crushed when I take a test and it's negative or when I finally start my cycle. I'm normally very bubbly and outgoing But it seems like every time One of those rare funks around the start of my cycle happens one of my coworkers has the need to comment on how "not to stress about it". With some of the newer ones being "put out better vibes" "the universe knows when it's your time" and while optimistic it's getting extremely frustrating.

I was talking to someone else about how she handles her precycle cramping and she pops in.

Coworker: maybe your pregnant

Me: that would be nice but I doubt that.

Coworker: (scoff) well not with that attitude.

As anyone who is TTC knows there is a point where in your journey you get discouraged. That there comes a point you can't let your hopes rise because you know the fall is the hardest. How/should I approach her? If yes: What would be a good solution that is still tactful yet clear enough that she can understand that this is a painful enough process without commentary or peanut galleries. If modern medicine and science hasn't helped I have little faith that "leaving it up to the universe" will either.  

Thanks in Advance!