neik

Hello Neik. Welcome to the forum.
If you want to build credibility as a theme developer you should really be working on optimizing your own site,
https://developers.google.com/speed/pagespeed/insights/?hl=en&url=https%3A%2F%2Fwww.themevault.net%2F&tab=desktop
A PageSpeed Insights score of 30 is really not good enough
 
Suggestions for better UX.
Use a honeypot instead of captcha in your contact form Get rid of the slidetoggle on the FAQ page, unless you plan to have longer answers. Why bother the user with having to click to reveal just one or two lines of text The automatic pop up will most likely just annoy users. Nobody will react to it before having a chance to read your offers. And google might punish you for it; https://www.theverge.com/2016/8/23/12610890/google-search-punish-pop-ups-interstitial-ads  
Most importantly: I think you need to work a lot on your brand and credibility. Let the user know who you are.
Your site has zero information about you: 
no images of you or your team no about-us page no info about your location, your pasion for design or your values, mission, vision etc. no testimonials from happy clients.