How can i tell if i have sent a reminder or if i have sent multiple reminders?

There are ways where you can check the reminders in your book, ritas1.

The reminders can be found out on the Invoice page. For additional reference, please take a look at my sample screenshot below:

Another way to find this out is by going the transaction lists of your customers. Here's how:

1. Go to Sales on the left panel. 
2. Select the name of the customer in the Customer tab.
3. In the transaction list, click Settings (small gear icon).
4. Put a check inside the Last delivered box. 

Please get back here if you have other questions about managing the email reminder in QuickBooks. Have a good one!