I think if you have a look through the forum you'll find the fact this is 'common' is true. Threads appear almost daily following spotting, then TVS. What is also common is the anxiety that accompanies all that, too, understandably. Waiting for a follow-up appointment for the necessary investigation heightens the anxiety.
But if you take a look at the outcome for all the ladies who have posted here about the above, me included, you'll find that by far the majority have good results in the end.
However, when you're in the midst of it, wondering what might/could be wrong, it's hard to think calmly. Try, if you can, to look at the experiences of other ladies here, whose anxiety was through the roof, and read how things ended for them. At the moment you are being dealt with appropriately by the professionals and hopefully you're in an area where follow-ups will happen fast.
All that to say, I'm sure before too long, you'll join those of us who begin to understand these things do happen to our bodies when we're on HRT and it's rarely cancer. I know words won't necessarily take your anxiety away, but you're not alone, so many of us have been there, and you know what? We're OK.
Sending a hug to you.