It was a long time ago admittedly but I started out my A Levels with subjects I didn’t connect with and definitely one too many overall due to pressure from my parents and school. After nearly crashing out of school entirely as a consequence I dropped down by one subject and swapped out another and was considerably happier. I know that school would have you believe that A Levels (then university) are the only routes to success but that simply isn’t true.
I was a secondary school teacher and was in a constant battle with the idea that “traditional” academic success is the only way to a good life. It wasn’t then and it isn’t now.
The real question should be do your future plans require biology for any reason? (E.g do you want to go into something medical or veterinary etc?) If not and it’s making you miserable, get rid of it. You would drop a subject for year two anyway and you’re much much better off doing well in three subjects than eh in four.
I understand your dad’s anxiety - esp if he is like many parents and believes a science is a “real” subject where art or graphics is not. My sister has a biology A Level and makes minimum wage at 35 years old. I am now a marketing manager and pay my chosen freelance graphic designer more than four times that and he makes his own hours and chooses his own gigs.
Education is a tool not a pre-requisite for a happy life. You use it to develop skills that will enable you to do something that will bring you satisfaction. It should not make you miserable. I know a job lot of people who failed all their A Levels and are doing just fine at life. I aced all my A Levels then dropped out of university - twice - before finally going back to get my degree at 23 because I had, by then, worked out what I wanted to do. Life is long and it isn’t a race. Do what keeps you healthy with an eye on the future to ensure you’re not screwing yourself later and you’ll be just fine