Hi there
Yes, you can do another A-level privately although this late in the year, it would be really hard to complete a full A-level and I would strongly advising against it. in terms of what subject you should heck, just pick one that you think you’ll be good out for example, if you were really good at English GCSE and do an English A-level there is no easy levels. It’s just dependent on how much work you put in and how much you really understand or enjoyed the subject. I understand how it must be hard Doing an A-level that you find difficult, but at this stage in the year I wouldn’t recommend starting some competing you instead. I would make sure that you split your revision evenly between each subject and try and look up past papers and go over what topics that you’re getting wrong, wishing you all the best with the exams.