I would think there are two other people who should be in on this conversation.
If it is just a hormonal balancing issue, you Endo should be in the loop. Mine asks about mood swings and feelings that I am having every visit and wants me to call her office any time things seem 'out of sorts'. She says feelings are more often the gauge of what is really happening then numbers on paper.
Your therapist can likely help quell depressive thought patterns that all of us experience at some point or another. You are not alone in this at all. My therapist is on call and I have picked up the phone more than once at an odd hour of the evening when things go grey.
No matter what, know that you will be ok. There has to be the times when things are mundane in order to know when things are rockin' awesome!