I have a mental health problem! (pregnancy related)

I've been married for almost 8 months now
I'm 22 years old not planning for a baby yet but this past 3 months every cycle I believe I'm pregnant for imaginary reasons and I believe I have pregnancy symptoms and af always shows up on time 
We're not TTC and we always use protection and never had a condom brake or anything slip anywhere! But I can't help it each month I make my self believe I'm pregnant please if you have any advice help me with this meaningless obsession of mine