Seven week old diaper and urine smells like ammonia.?

Most likely normal. More common with cloth or re-useable diapers.
7 wks baby urn ammon. Normally babies urine does not smell. But if urine is concentrated it can smell of ammonia. Mke your baby is getting enough milk and you can gise small amont about 2 oz of water once or twice a day.
It happens. Urine is named for urate, the salt produced by protein breakdown and eliminated in the pee. Urates break down to ammonia over time. Todays super absorbent diapers pull the urine into their weave faster & it allows time for the ammonia smell to develop if you are not changing often. It is not a sign of disease.