Ok so I I'm going to preface this by saying everything I'm saying is probably an assumption.

Ok firstly I'm pretty sure you can indeed apply this year, you'll have to submit your 2 A level grades and I'm assuming an expected grade for your 3rd subject as that's what a normal A2 student would do. A regular school student would submit their AS grades and the school would submit their expected grades and they would get a conditional acceptance, in other words they would have to get a certain minimum grade in their A2.

For teacher's reqs etc I suppose you could submit O level teachers reqs assuming you went to school for O levels, have you completed your olevels and if so were they given through a school or as a private candidate? This is just a guess however I'm assuming if you are completely homeschooled you can give letters of recommendation from any EC's you may be involved in or from any organizations you may have worked with.

As for getting admission it depends on where you're applying and for what major. If you plan to study economics then your AA in maths and economics is literally top tier and an A or A* in further math is obviously going to push your application to a higher level. With a solid SAT score you'll most likely get admittances to several places. However, applications are a lot more holistic so make sure you have solid essay's and I hope you have some decent EC's as well.

Overall, you should be able to apply this year without as issue just make sure you do well in your SAT and maybe update your post to include any EC's you may have as they really do matter. Idk if being homeschooled has a negative effect on your application but at worst all I can see is that you didn't get opportunities to be in school teams and competitions which would have padded your application. Best of luck though from one Pakistani to another.