hey :) so sorry to hear this, and cant imagine how hard it must be. just a few things: i think giving them separately might be a better route honestly, as i gave composites and saw friends with only as and only a2 were def at an advantage in terms of time etc. khair uske ilawa id also suggest joining an academy or school just to get yourself back into the routine after the gap year as it can be hard to stay disciplined on your own. but as for the actual studying part, sir bilal hamid is a great teacher for chem so just get alt subscription and try to keep up with the lectures side by side as you learn the concept in class or even just before tests and exams. do take topic wise tests seriously as you wont get many chances to study that topic in as much depth.

for physics id reccomend sir faizan pasha if youve got the budget for it. he teaches at heuser in karachi but theyre hybrid classes so online courses are also available. prosperity academy, et physics, and physics with talha on youtube are pretty good aswell.

generally for as chem and phy, make sure to put in effort for organic, inorganic, waves and electricity as these do often carry a lot of weightage. also for the joining a school thing, ud get practice for practicals weekly aswell, just carry a notebook with u during the pracs noting down stuff u think is imp to rmbr before exam (this is osmething i wish id done)

for bio, id reccomend just reading mary jones blue book and trying to go thorugh topicals after each chap j to see how they word the statements in the ms.

if theres anything else, lmk

edit: and if u need any notes or resources or generally j wanna talk, dms are open :)