What is the diagnosis for PMDD and how do i confirm I have it?

Hello, thank you for taking time to read this. I'm a 19 year old female and i have had a past with hypothyroidism when I was 15 and IBS, apart from that I am healthy and have nothing except my studies to worry about in life. 4 months ago I had a meltdown and i almost tried to kill myself. I started noting down my actions because I thought I am bipolar, I have had suicidal thoughts before but never actually went for it. I assumed I am looking for attention and i tried to ignore it. A month after that was normal except the random tears I'd shed for no reason, then i found out about pmdd, my meltdown happened a week before my period. Last month, i did it again. I hurt myself and prayed to God i die. I got scared that i might actually kill myself. That also happened on day 23 of my menstrual cycle. I am currently a week away from my period and i just feel lazy or occasionally sad so maybe it's not serious. I honestly don't understand myself. I see checking out many PMDD symptoms but at the same time I think i might be lying to myself to avoid being responsible for my actions. I am still tracking my my mood swings. I don't want to tell my parents because they might think i am overthinking, also I don't know how to tell them I tried to hurt myself. My mom will be overprotective of me and the last time she did that it was overbearing. Thanks again.