It could be the custom coding, but we wouldn't know for sure unless it is switched to a standard theme. You can actually save your theme and it will show up in the theme options so you can switch back at anytime. The thing to watch out for when switching themes is the content in the header area. I don't know the exact reason (Adam may know) but anything in the header area would have to be recreated. I like to make a copy of the site first so I can test out the switch on the copy site in case anything goes totally buggy. As far as running into any future issues, unfortunately, it's hard to say. If an update is made to the original theme that you customized the update may not be compatible with your coding. As you can imagine, it would take a TON of resources and time for us to comb through every account with custom coding to find where the error is occurring- this being a big driving factor when it comes to our support center not being able to provide assistance.
With that said, community is definitely where you would want to be regarding these questions. If you want to post your site and edited code someone will take a look for you! 
Thanks for your reply and info 🙂
If someone could please take a look - http://www.adiabeticsmenu.com/about.html
(website not fully launched yet so other areas not accessible)
So the problem is that my mobile navigation isn't working... I click on the three horizontal lines and it just comes up with an X. But on desktop, no problem. Also, if someone can help me to get the logo text centered on mobile view too that would be amazing! Thanks for your help 
Here's my header code: (let me know if you need anything else... I have been making incremental chnges based on online tutorials /very small knowledge myself of coding)
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
</head>
<body class="header-page">
<div class="wrapper">
<div class="unite-header">
<div class="nav-wrap">
<div class="container">
<label class="hamburger"><span></span></label>
<div class="logo">{logo}</div>
<div class="nav desktop-nav">{menu}</div>
<div class="nav membership-cart">{membership}{minicart}</div>
</div>
</div>
</div>
<div class="banner-wrap">
{{#header}}
<div class="container">
<div class="banner">{content}</div>
</div>
{{/header}}
</div>
<div class="main-wrap">
{{#sections}}
<div class="container">{content}</div>
{{/sections}}
</div>
<div class="footer-wrap">
<div class="footer">{footer}</div>
</div>
</div>
<style>
#wsite-title>ADM.</span> { display:none; }
</style>
</div>
<script>
(function(d) {
var config = {
kitId: 'nxe1ajf',
scriptTimeout: 3000,
async: true
},
h=d.documentElement,t=setTimeout(function(){h.className=h.className.replace(/\bwf-loading\b/g,"")+" wf-inactive";},config.scriptTimeout),tk=d.createElement("script"),f=false,s=d.getElementsByTagName("script")[0],a;h.className+=" wf-loading";tk.src='https://use.typekit.net/'+config.kitId+'.js';tk.async=true;tk.onload=tk.onreadystatechange=function(...)
})(document);
</script>
<script type="text/javascript" src="/files/theme/plugins.js"></script>
<script type="text/javascript" src="/files/theme/custom.js"></script>
</body>
</html>
Hey... Me again.
I can't figure out how to post a new post on here to ask for help on another issue I have just come across 
Was hoping you could please help me with this too.
I have just noticed that the alignment of my photos differs between the editor mode of weebly vs it being pubslihed.
I have attached photos from the editor in the first 2 pictures (where the photos align themsleves perfectly as per the dimensions I have arranged of the elements) vs. the published view shown in the last 2 pictures which ... well you can see it is not what I was wanting
I went from being so close to finally finishing my website to now having to deal with these issues I never could have forseen as an issue (mobile navigation and my editing alignments not reflecting the final product)
😫🤯😑
