Unbearable Anxiety - 6weeks Pregnant

I feel physically sick at the moment and it's not morning sickness. I know because I had morning sickness with my daughter. 
It's severe anxiety. 
I'm so convinced that I am going to misscarry that it is ruining my life. I have no reason to feel like this and I do suffer with Anxiety disorder anyway but this is crippling. Im very mildly crampy and was with my daughter. I've had no bleeding and no previous miscarriage but I can't get it out of my head that it's too good to be true and I'm not going to come out of this with a baby 😞
I'm driving my husband mad and I can't help it. Every feeling I get down there is because I'm having a miscarriage ... my slight nausea is a coincidence .... my sore boobs are a coincidence .... I can't get over it.
I posted on here previously and returned online to find messages basically telling me I should be worried .... and there's nothing I can do about it. I know this ... I'm not thick... i just need to vent and maybe there's another lady out there also suffering who can identify. 
I feel sick everyday with anxiety and can't even talk about the baby without feeling certain I'm going to lose it, like I don't deserve to have 1 healthy child let alone 2. 
I wish I could just switch off until my first scan at 7.5 weeks next Saturday but waiting for that day is crippling me. Just to know there's even a baby growing. Phase 1 😑
I have my doctors appointment on Wednesday and don't known whether to mention it to them and get some advice on how to deal with my feelings as I fear they will get worse and are destroying my mental health. 
Thank you for whoever makes it to the end of this rant  xxxxxxxx