I'm not sure if I have postnatal depression and I'm stuck

I know that I should probably go see a doctor if I'm unsure about this but something is holding me back from doing so, I don't even know if I should post this or not 😕 My son is 11 month old and I think I may have postnatal depression but I'm so scared to go see a GP, my head keeps telling me that if I do then social services will get involved and take him away from me. I just don't know what to do. I've went through the 'baby blues' phase and kept telling myself for months that it's just that but I've recently discovered that baby blues doesn't last for months and typically goes away in a few weeks. Over the past months my symptoms have became a whole lot worse. I'm irritable all of the time, constantly crying and feeling helpless. I beat my self up all of the time because I don't think I'm doing a good enough job and most of the time I sit and think "why the hell did I decide to become a mother" I've also had awful thoughts of giving my son up for adoption,harming him, walking out on him, harming myself (which i would never ever do anything to harm him or neglect him) and I feel so so guilty. Now it just seems like I can't do anything, I can't sleep, I can't eat. I'm always so stressed over nothing and I just don't know what to do anymore. Its getting so hard to cope by the second and I'm stuck.