Following Lie Ryan's advice, my recommendation is to start fresh. Although it may seem daunting given all the hard work you've already put in, attempting to fix a flawed foundation will only result in more unnecessary complexity. In the end, you'll be left feeling overwhelmed with a shaky website that might look fine at first glance, but one small error could cause everything to crumble.
I liken this situation to arranging a room. You begin putting things in place, only to realize the bed blocks the desk, you forgot about wanting a piano, there's no space for yoga, and reaching the dry erase board on the wall is impossible because of the dresser obstructing it - the list goes on.
You have two options: try to make do with what's already there by moving things around, adding new elements, and cluttering the space even further. Or, clear out the room completely, visualize a better layout, and gradually reintroduce each item in a cohesive way taking into account everything you missed the first time around.
The same principle applies to your website. Restart the design process armed with the knowledge gained from the initial version. I assure you, your code will be neater, the site will look and function better, and future updates will be simpler.
When starting afresh, consider the smallest screen size possible. Ensure your site looks good at 320px width before expanding and adding breakpoints along the way to achieve full responsiveness.
In a recent article titled 7 Habits of Highly Effective Media Queries, the author quotes Stephen Hay on effective responsive design: "Start with the small screen first, then expand until it looks like shit. Time for a breakpoint!" This highlights the simplicity of the approach.
Finally, prioritize using pure CSS over WYSIWYG editors. While editors are convenient, having a strong grasp of coding will serve you much better in the long run.