Add a new rule to .htaccess whitout overwrite https server rule - .htaccess

Question

I have a problem when I try to add a new rule to my .htaccess. On my server I activated a rule which redirects http to https and it works fine but when I add a new rule to my .htaccess then https disappears.
My .htaccess
<IfModule mod_rewrite.c>
Options -Indexes
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)$ index.php?$1 [L]
ErrorDocument 404 https://%{HTTP_HOST}/
ErrorDocument 403 https://%{HTTP_HOST}/
</IfModule>
I need to redirect every request to index.php (mvc) and it should work together with https.
I tried deactivating the redirection from the server and to write everything into my .htaccess like this:
Options -Indexes
RewriteEngine on
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.example.com/$1 [R,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)$ index.php?$1 [L]
ErrorDocument 404 https://%{HTTP_HOST}/
ErrorDocument 403 https://%{HTTP_HOST}/
But I get the error The page isn't redirecting properly. How to fix it? Thank you.

Answer 1

I've finally solved it with the help of my internet provider. This is the final code:
RewriteEngine on
RewriteBase /
# force https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteCond %{HTTP_HOST} ^www.
RewriteCond %{HTTPS} off
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301,NE]
# redirect to index.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?$1 [L]
ErrorDocument 404 https://%{HTTP_HOST}/
ErrorDocument 403 https://%{HTTP_HOST}/