Wow, Fiona, how I can relate. I went through a period when I was almost shaken by fear of exactly such things - thoughts coming true, fears coming true... it was one of the worst periods I ever went through in my life I think. It is all so... without boundaries, my brain would come up with more and more stuff to be afraid of... I was almost losing my mind I felt.
So I can kind of imagine what you must be going through right now and I am really sorry to hear all this!!
I still get it sometimes a little bit, that once I think of something (even really fast) I kind of fear that it must mean something. That again is the typical OCD thinking: Thinking that everything we think means something. Similar to intrusive thoughts... most people get thoughts like that, but just shake them off, maybe laugh them off, and forget about them. Somebody with OCD will give importance to the intrusive thought, and try to NOT think it, and usually if we try to NOT think of something guess what we'll be thinking about... thus the vicious cycle evolves.
Now with the fear of things coming true - you know, I am not saying that I don't believe in anything supernatural, that we can sense things, etc - BUT!! You need to remember that you do have OCD, and that the OCD is on the lookout for ways to scare you, and will make you think of exactly those thigns you want to NOT think about - right?
I remember - OK, TRIGGER CAUTION, I am going to talk about a specific fear now - how somebody told me, "no, you can't cause an earthquake by thinking about one, you don't have that much power, maybe thoughts would have the power to cause something that affects you, but not so many people..." And oh how I was relieved! Ha, for a few hours. Or was it minutes? That same night I kept obsessing about how he said it COULD affect something that is about ME (that guy was himself into magic and willpower stuff and maybe a dangerous person for me to talk about this at the time), anyway, suddenly it hit me and I thought, so what if I started fearing something could happen to me, like a heart attack? And POP that thought was in my head, and I started obsessing about specific dates I might die at and maybe my thoughts about those dates might make me die then....
It helped a little that my Mom told me about a dream she had had about dying at a specific age, and she was afraid then, but still she didn't die at that age. But the "what if what if what if" kept going in my brain.
And mostly it was not really about being afraid of dying, but more about
: How will I live with that fear all the time until then???!!!
It got so bad that I had a really hard time chosing a pin number for my bank card because I was afraid of obsessing over the numbers... Yikes, just thinking back of that time makes me feel nervous!!!
Now as I said, it is not that I don't believe we can sense things, but neither do I believe that the world functions in that OCD way. No no no. What really has helped me (apart from prozac)

is my faith. I do believe in a loving God, and that there is more to all this than just "if I think this, it will happen". I mean, try it out. Think that there will be a million dollars lying in front of you on the table within the next minute. Well, did it happen?
I just hope that maybe something I said could help a little bit... Maybe just saying I have been there? I am so so so very sorry you are having to go through this. Remember it is OCD making you worry like that. We kind of CAN tell what is OCD and what isn't, can't we? If it causes that special OCD type anxiety...
Sometimes it is best to not even let the thoughts start. Especially since I have been taking medication I have been really good at not even letting the wheel start rolling, so to say. So try to distract yourself and just act as if the thoguhts weren't there and don't follow them around and let them take you ever more scary places.
By the way, have you talked to your Mom about those fears?
Bye for now and let us know how you are...
Kathrin