I need a Shopify Expert with intensive knowledge with Facebook Pixel

There has been this stressful issue me & my FB advertiser have been dealing with. The anaytics in fb is wrong, it's say twice more purchases then it should. (That is our assumption cause my Shopify store said way fewer sales than what it said there). A scenario would be: It says 2 people "added to cart" ----> 1 person "checkout" -----> 2 people "purchase". It makes no sense since only 1 person checking out and our store had way fewer sales then the total said on FB. We have FB pixel properly installed on our website. We haven't installed or updated our theme. No FB ads apps installed. What we urgently need is: - Deep Scan (and I mean a rigorous inspection) of our Website to see if there's any code/script/app causing the issue - Check if FB pixel is, indeed, properly installed - Fix the FB pixel firing twice issue, particularly on purchase event 2 goals: - Prevent FB pixel from firing twice (especially on Purchase events) - Making sure that I have accurate insights, or at least Shopify and FB data in sync.