Unfortunately yes, your worry is typical and completely understandable. There honestly is nothing to be done but to wait for the testing process to be completed, and I'm afraid that's likely to take anywhere between 1 and 2 months. I won't say "don't worry", because it's perfectly natural to be worried, but try to put it to the back of your mind and get through it a day at a time.
The only bright side is that with a PSA of 11, if you do have prostate cancer (and you may not, of course), it's overwhelmingly likely to be localised and hence you'd be on a curative treatment path.
A biopsy will probably follow the MRI scan (nothing to be concerned about) and if that were to find cancer, a bone scan would then follow. For each step in the process - MRI, biopsy and bone scan - there's typically a 2-3 week wait for results.
If you've not already done so, do download the information sheets from the site, and give the wonderful PCUK nurses a ring on the Freephone number at the top of the screen if you have any medical questions.
Best wishes,
Chris