Lots of things can cause a raised FIT test and if it's only slightly raised, the odds are it's caused by something really minor like a hemorrhoid or a fissure. The struggling to poo alone makes a raised result fairly likely as you straining can cause hemorrhoids or a hard poo could scratch something and cause bleeding.

Thanks for your reply  I'm just worrying myself a bit because of the other symptoms I've been having as well. Going to try to speak to my GP again although that causes anxiety in itself as it's so hard to get an appointment these days. Fingers crossed