Getting sad when my period comes

So the last 6-8 months I’ve been getting outrageously sad when I get my period. I’ve always had pretty severe PMS where i’m super irritable, emotional, and sensitive. Lately it has been different and I was wondering if anyone else has gone through something similar. I am only 20 and I am not looking to be a mom until 5-10 years down the road. When I get my period I feel like i’m mourning the fact i’m not pregnant. i feel like someone died and I get so sad. This has never happened before and it’s such a deep feeling I cannot shake it. I don’t want to have a kid right now and I don’t know how to get my “subconscious” to agree with that. Any advice or similar stories?