We are a team of designers and developers with expertise and experience in Photoshop, HTML5, CSS3, PHP, AJAX, JQuery, Angular JS, XML, Wordpress, Joomla, Shopify, Bootstrap, CodeIgniter, Laravel, Google Map API and MySql.
We have delivered several Wordpress sites and all of them are responsive. I have seen the form and the issue on smaller devices. You have rightly surmised that iframe will not work.
I am confident of delivering as required. I request you to share the admin access and CPanel access.
I ensure a very thorough job and also support if you need changes / enhancements in future. I look forward to hearing from you and working on the project.