when does fearing your child’s death become not normal?

So I know that all parents have the fear of losing a child or even family members/spouse but when do you think it’s too much? I constantly think about it and the worse things pop into my head all day and keeps me up at night and i’m miserable because of it, i cannot take it, i’m scared to leave the house a lot because of wrecks, i’m scared all the time even over outrageous thoughts, i was on depression and anxiety medicine but i’m pregnant again and had to stop the medication i was on, i would like to get back into therapy but i’m wondering how much worrying is too much?

also, can someone explain intrusive thoughts? i believe that’s what keeps popping up in my head but i don’t want to sound crazy.