I'm a developer and an SEO, I can help you with your website speed as well SEO.
I use most of the famous tools like ahrefs, semrurh, moz, serpwoo etc to get a detailed report about a site so that I can take necessary actions. I will check on-page SEO and what you need to do get your rankings back. Also, I will suggest you whatever is needed to beat your competitors.
I don't work in this much price normally because I'm new here, I'm doing it.