I'm no expert but from what I've read (online, so you can probably take it with a certain pinch of salt), false negatives are possible but relatively rare. I had the guaiac test some months back, which is supposed to be far less accurate than the FIT test and my doctor seemed fairly confident that if that were negative, the bleeding I was getting was clearly external and I did not need a colonoscopy. (As it happened, I developed further symptoms and another doctor said to go ahead with the colonoscopy which confirmed hemorrhoids and found nothing more sinister, thankfully.)

The specialist also said that at my age (40) cancer was the least likely option, less than 1%, but that a colonoscopy was the only way to be certain what was going on so he would recommend one.

My impression also is that your symptoms could be caused by many things. That's not to say they shouldn't be investigated, but if you are having no bleeding, the FIT test is negative and you are not in a high risk group, then cancer is probably a long way from the most likely option, especially if your doctor isn't worried. I know that is limited reassurance though.

I really appreciate your reply an thank you for some reassurance. What got me worried was a comment in colon cancer related forum where someone wrote that they had Colon cancer twice an both times fit test results came back normal which threw me back in "what if" stage of worry. 
Did you experience any pain with hemorrhoids? 

Not in my abdomen. I had some itching and stuff in my anus.

And yeah, I know the feeling. I was very worried when I read that the guaiac test was considered to be much less accurate than the FIT. But of course, we hear about the cases where something is missed. People don't tend to post saying, "the test was negative and that turned out to be correct," even though that is far more common.

Yes, the fear of missing something is very disturbing and the fact that most people who are eventually cleared despite their symptoms rarely follow up with the final outcome on forums is not helping. You are just left wondering. 
So big big thank you for sharing your outcome. 
 

have a nice Sunday. 
 

UPDATE: I did a private colonoscopy today (5.11.2021) and it turned out to be nothing except some internal hemorrhoids.