I see two options. 1) - let them do it. Give them list of requirements, 2 days, then pass it to QA and let them deal with all the fixes. Then measure how much t

I see two options. 1) - let them do it. Give them list of requirements, 2 days, then pass it to QA and let them deal with all the fixes. Then measure how much time it actually took to get 100% of required functionality. That's the best way, but requires their cooperation - usually forced from above. Alternatively you can try to split features you working on into detailed tasks (adding a button: add a button, test in browser 1, test in browser 2, write backend logic, write tests for backend logic, deploy, etc.) detailing how much time each step can take. This will make you job more visible. Some people are not fixable though.