I felt the same when my children lost their dad. I couldn't stand the thought of them having to go through watching me die as well. Like you, I felt the world was as unsafe place, I knew how quickly life could change and I know what it is like for children to grieve for their parent.
So my HA was a way of controlling that. Of course it doesn't work, I can look for signs but ultimately any one of us can get cancer and many of us will at some point in our lives but equally any one of us could get hit by a car, or be in a place where a terrorist attack takes place... or.... the list goes on. We can't live that way or you would live life in fear, like you are doing right now.
You have been through one of the worst things a human can go through, you also have pregnancy hormones on top of that. It's not surprising you are struggling right now.
Your husband might be concerned but if you weren't so anxious he might not be. My husband would never have been concerned about my mole I had until I spent so much time pointing out to him how it could be cancer, how it had all the signs. It is always best to get anything like this checked out, if it hasn't started to heal by the end of the week then yes, you certainly need to see your dentist but that doesn't mean it is cancer. It just means it needs checking out by a professional.
If you can't wait until the end of the week then see your dentist earlier if that is what you feel you need and if you can get in.
I feel so badly for you, I know how you are feeling and I wouldn't wish that mental pain on my worst enemy. It's soul destroying and when you have dealt with this ulcer you need to get on top of the anxiety so you don't feel as bad as this again. You can control it, you can get better and you will get better, with a lot of work, possibly medication and a lot of support. And I will virtually be with you as will many others here 