Is it possible to run custom validation rules on Attachment control based on another control value?

Hello all

I am trying to setup custom validation on attachment control in Nintex Office 365 forms. 

Here are my rules:

1. I have a panel that will be displayed  or hidden based on the value choice type control value.

2. If choice = yes, I display panel. 

3. The panel has attachments control. 

4. I need to validate that the attachment control has 2 attachments only when choice type dropdown's value = Yes 

I saw some JS functions on how to count attachments. But I don’t think we can run custom js functions on attachment control in Office 365 forms. Is it possible to setup this validation in form submit?

TIA