Wordpress Troubleshoot and Traffic Issue Expert

Hi
I was wanting to get some help with my website ---------- .
The website has been going for a number of years and originally when I set it up I had two purposes, one was to provide local clients for my career counselling services and secondly to provide a global content site for careers ---------- currently has around 50 to 60 pages of content and has successfully provided local clients for me for several years through organic search results. But I haven't done any serious work on the global content for a number of years. In December 2019 I transferred it over from a proprietary website builder to ---------- July 2021 I suffered a massive drop in traffic almost to 0 but due to other things going on and with covid issues I never got to address it until April this year. It turns out it was a permalink /HTML setting that I had inadvertently changed in WordPress. My traffic has not recovered yet although it is showing a slight increase since the permalink issue was fixed.
What I want help with:
A. Confirm that the permalink/HTML issue was the only cause of my traffic drop.
B. Get some idea on weather my traffic is likely to return to previous levels and if not what I need to do about it?
C. Identify any other glaring problems with my website (I'm sure there are a number).

I would also like to get some advice on whether I should start a new standalone website on DIY resume building. Resume content is covered somewhat in my site already but I have some new ideas for new products and monetisation and wondering if this would be best done on a separate website or incorporated into my existing site.
Could you please provide some idea of cost to address these issues?