Best practice how many fields in one screen for mobile and desktop browser

my website is using bootstrap so its a responsive not the adaptive one.

I want to make a form that has many fields->i already breakdown as a section and cut down unnecessary fields, for example one section has 17 fields.The amount of fields must be the same for mobile and desktop browser.

When i tested on desktop, user isnt overwhelmed with the amount of fields in one section, but when it comes to mobile, user has a long scroll to reach button(next-> to next section or prev-> to previous section).

Anyone know from experience what is best practice for form like this? Like how many max fields that i should have.