if you want, you cna test yoru ammonia by taking it to the lfs. Many of them will do free water tests. And double check your numbers.
Did you ever have any nitrites?
if so then I would definitely have the water tested, it coudl be your kit or the way you are doing your tests tool
Since you used shrimp, before the LR, then it may be that you have cycled and the ammonia is a false reading too.
If this turns out to be the case, then leave the tank empty for about 2 more weeks adn make sure it is stable, then go ahead and start adding fish