Install RSfirewall & Akeeba backup but if you purchase the pro version of Akeeba backup it can create backups automatically and upload it to remote storage automatically on a schedule. The firewall does a good job at protecting the website code even if a security issue becomes known within it. Remove any extensions you are not using.
Login to your Matamo panel and you can find it it in Behaviour -> pages it will show you what pages people have been on . Count how many people were on your cart page vs how many checked out.