My form is very hard to use on mobile devices, to the point where it almost cant be used

I took a look at your website and the form itself.

I see that there are 2 things causing the same:

1. Your website has a lot of scripts loading so it takes a while to load all of them and then takes a bit of resources to run the same

2. the form you are using is quite large.

The two do not seem to go together too good.

What I would suggest is to either:

1. move the form to a page where you do not have as many scripts or

2. have a link to the form present on your form instead of it being embedded. That will help your users to open the form and fill it out without any issues

3. split the form into 2 or three forms instead (step1, step2, etc) which would allow you to show smaller forms and collect all needed details.