People do the entire A-level in a year and get an A, you'll be doing A2 plus building on AS, it's possible but only with resits and hard work! You'd also need to question your personal motivation to the subject, I understand personal circumstances can make things tough but do ask yourself if there's another underlying issue like the teaching style, the syllabus, the stress, etc. And then find a way to work with it, without solving any underlying problems you'll never be able to do your best