@
miggy
Testing should be part of your hobby mate, I know it's 10 litres and most will think what is the point but if you start now and get that right then moving up in the future you will have the skills in place to keep more advanced fish.
Also as you are having a few issues then it's for the best that you test so you can see for yourself your tank water
Fish are just as much a pet as another animal... I can hand feed my marine fish, when I go up to my tank they go crazy lol (hungry lmao) but if your dog is sick you take it to the vets, you can't take a tank to the vets lol so the best thing you can do is test yourself and rule out the obvious.
But until you have your test kits and tell me your results there is not much we can do... but waiting every week to see what a shop says is a little bit crazy, for me I would suggest that you get the kits and test daily see the changes, once you get the water you require you can test once a week/month or something like that
Also really important, take a vile of water that you use for water changes... get the water tested before you put it in the tank.
So if you do not want to test yourself, then take 2 water tests to the shop....
one test for your existing tank water.
one test for the water you have cleaned (chemical) and would use for the water change.
you might be putting nitrite into the tank yourself with the water changes, that would be a cycle you would never get out of unless you test the water you are putting in!
Regards
Mick