Sorry that you're still having problems with this issue. As you are not hosting with us, it really makes it difficult for us to determine what's actually in your .htaccess file. We would need to see the entire thing to judge what's happening in that file. You should make sure that the re-write rule is occurring first. If there are other rules in there that affect the URL, then they might be nullifying the changes that are needed. If your settings are correct and you're STILL not able to see the HTTPS for all of the paths, then you may need to take some time to address OpenCart directly. We did not write the code and while we often help our customers or anyone using the software, you may be better off directly asking the creators of OpenCart
for assistance. Especially, if you're still not seeing the results after we have provided what we believe is the best answer. I can't see your database nor installation files. And when I check the urls to see why your HOME page is not showing as secure, it's because of the following:
This list of URLs comes from looking at the MEDIA using the Firefox browser when checking the SSL link. It lists all of the media file links. This often shows why the page will not be indicated as secure due to the mixed list of http and https links used by the media files that are elements of the website.
Note that several of the paths are set for WWW and are NOT set to go to HTTPS because of that. You will need to adjust your configuration to account for the WWW definition and that should hopefully cover it all. Just add another line for the WWW definition of your path in the configuration.
In terms of the behavior of the entire application not using the https link, you will need to ask OpenCart why the fix that we previously gave is not working. That fix came directly from their forums. If there's something else going on on your site, then they may need to look at it for you.
Sorry again for the continuing issues. I hope that the information that I have provided helps to get you a quick resolution.