Have you been doing partial water changes? How much and how often?
I would suggest doing a 50% water change and then dose the tank with Prime.
Test your water every day. If ammonia + nitrite <1, dose tank with Prime. If ammonia + nitrite >1, do a 50% water change and then dose tank with Prime. Prime binds ammonia and nitrite for 24 to 48 hours, up to 1 ppm the combined amounts. So for example if ammonia is 0.5 and nitrite is 0.25, the combined total is 0.75. You could dose your tank with Prime (7.5 mL would dose your tank) and your fish would be protected from ammonia and nitrite for 24 hours. They are both toxic to fish.
You will be cycled when ammonia and nitrite are both 0, and you have some nitrates. Then you will do water changes as needed to keep nitrates below 40 (some keep them below 20). Most people do weekly partial water changes.