htaccess force ssl except for rss feeds - wordpress

Question

My site currently forces SSL everywhere. This is the way that I want except that it is causing issues with my RSS driven newsletter and feedburner. Due to this I need to make exceptions for my feeds.
Can someone help with the proper htaccess rules to pull this off?
My feeds are
/feed
/shop/feed
/forum/discussions/feed.rss
Here is my condition for forcing SSL. This works except that all RSS feeds are forced to.
# Force SSL
RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} !^/forum [NC]
RewriteRule ^/?(.*)$ https://photoboothowners.com/$1 [R=301,QSA,L,NE]
I tried the following but it did not seem to work correctly.
# Force SSL
RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} !^/forum [OR]
RewriteCond %{REQUEST_URI} !^/feed [OR]
RewriteCond %{REQUEST_URI} !^/shop/forum [NC]
RewriteRule ^/?(.*)$ https://photoboothowners.com/$1 [R=301,QSA,L,NE]
Your help is greatly appreciated!
Update: This is my current .htaccess file in the root of my server. This is currently redirecting http://photoboothowners.com/feed to https://photoboothowners.com (notice it is dropping the feed directory).
RewriteEngine on
# Use PHP5CGI as default
AddHandler fcgid-script .php
RewriteCond %{HTTP_HOST} ^buyaphotobooth\.net$ [OR]
RewriteCond %{HTTP_HOST} ^www\.buyaphotobooth\.net$
RewriteRule ^/?$ "https\:\/\/photoboothowners\.com\/starting\-a\-photo\-booth\-business\-build\-or\-buy" [R=301,L]
RewriteCond %{HTTP_HOST} ^photoboothforums\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.photoboothforums\.com$
RewriteRule ^/?$ "https\:\/\/photoboothowners\.com\/forum" [R=301,L]
# Force SSL
RewriteCond %{HTTPS} !=on
RewriteCond %{REQUEST_URI} !^/forum [NC]
RewriteCond %{REQUEST_URI} !feed [NC]
RewriteRule ^/?(.*)$ https://photoboothowners.com/$1 [R=301,QSA,L,NE]
RewriteCond %{HTTP_HOST} ^photoboothowners\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.photoboothowners\.com$
RewriteRule ^how\-to\-use\-our\-premium\-print\-designs\-in\-breeze\-dslr\-remote\-pro\/?(.*)$ "https\:\/\/photoboothowners\.com\/how\-to\-use\-our\-photo\-booth\-template\-designs\-in\-breeze\-dslr\-remote\-pro$1" [R=301,L]
RewriteOptions inherit
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
RewriteCond %{HTTP_HOST} ^.*$
RewriteRule ^shop\/photo\-booth\-layouts\-and\-samples\.html$ "https\:\/\/photoboothowners\.com\/shop" [R=301,L]
<Files 403.shtml>
order allow,deny
allow from all
</Files>

Answer 1

Your rules are using OR so they read as:
if server port is 80 and the request is not forum OR it is not feed OR it is not shop/forum
That's going to match everything. Get rid of both of the [OR] so that the match reads:
if server port is 80 and the request is not forum AND it is not feed AND it is not shop/forum
EDIT:
Per your updated question, the following line is missing a slash:
RewriteCond %{REQUEST_URI} !feed [NC]
should be
RewriteCond %{REQUEST_URI} !/feed [NC]