@Lucagu 

Consider using the app as I mentioned earlier.

Another option, you can utilize a 3rd party app to create estimates/invoices for free up to 1000 invoices. When your customer accepts an estimate, the app automatically convert it to an invoice and send it out for payment. You will need a paid connector to duplicate the transaction automatically to your QBO account, a payment processor (e.g PayPal, Stripe), and another app to reconcile PayPal/Stripe transactions into QBO.