No, strategy is efficient, unless and until you follow it. If you rectify your mistakes you can surely achieve your desired score. So I think you should also make a list of what mistakes you committed, make a list of your weak topics in all subjects.
Bro first stop thinking you have less time etc different things. Just stop overthinking and calm down take a deep breath. When you are calm there is no need for you to plan stuffs or whatever you will be in a flow and make plans on spot etc or even if you do a plan prior you will be confident in it and yeah maybe sometimes in future you might feel it is kinda incorrect it is okay you cant be right everytime you will learn from your mistakes, chances are less for you to make big mistakes ig if you are like in awareness but chances are there for any mistakes we dont know how big but everything for our good.
(If you feel sad understand that ,that feeling is valid and understand the reality , accept sadness as you accept happiness. And do what you have to do depending upon the situation.)
See a lot of time is there. Just see you got 24 hours per day. Even if I take 8 hours of sleep and 4 hours of other things, you got 12 hours to study (or consider 10). How you utilize these 10 hours is important. Join a good test series and study according to the syllabus of every test. See I know they will ask things which are not needed but you focus on the Ncert and syllabus part.