Swapping A-levels

Hi, I’ve decided to drop psychology after AS exams and take up chemistry as it is required in the degree I’d like to do which is biochemistry, and that I feel I might enjoy the subject now even though at gcse I didn’t really have an interest in it. I don’t really remember it to be honest but since looking at my friends text book it looks quite enjoyable (especially compared to psychology). I do maths biology and psychology a levels and was considering doing both AS and A2 chemistry in the same year as A2 biology and maths next year, but I know that would be pretty stressful as I’d like at least AAB and probably not recommended so I guess I’ll have to do a third year which shouldn’t be to bad? I’ll be able to get a part time job and maybe go travelling for a couple of months after the chemistry exam. Is that achievable with an A2 commitment as well? Also, I’m wondering if I would be at a disadvantage when applying to uni after doing 3 years of a levels. Would they know that I changed my mind and didn’t actually resit any exams?(which I hopefully won’t need to do). And do they look down on changing your a-levels? Thanks

Its going to make no to very littel difference for uni.
The real issue is have your school agreed to let you fast track or offered year 14?
Are you a UK or an international student?

I’m a UK student and haha this question may seem familiar to you as I asked it somewhere else and I just realised I didn’t actually reply to you sorry about that. Yes i am allowed to do a third year in my college and they have considered allowing me to do fast track chem along with AS and A2 biology, but they weren’t very keen to allow me to to do as, as I am aware, it would be difficult and stressful. They’ve told me to get exams out of the way and then come back and I may have a meeting with the head of chemistry to see if I’m viable. I’ve thought about actually learning AS chemistry during this summer coming and practicing past paper so I am up to a standard where the workload may not be as bad. But either way having four to do in one year does seem very stressful.