The most common reason why you can't see your done forms is an unstable internet connection. After finishing a form your device tries to upload the results in your account.
If this is not possible the app shows a warning about that and saves your results on your device.
As soon as the internet connection is stable again the app will upload your results to make them visible in your whole account.
If you want to check if this is the case, you can do the following:
In the menu of your app you will find your outbox.
There you can find all your saved results, which weren't uploaded yet.