I can't really give a full answer here because I've only just finished my AS year, but I'll give a bit of insight.
I take 4 subjects (History, English Lit, Psyhology and Law) and will be continuing all 4 on to A2.
I'm also currently: doing an EPQ; working part time; have my horse that I have to see to every day; am studying for admissions tests and my driving theory test along with work for university schemes and online courses I chose to do, and surprisingly I do also have a social life!
I just got 4 As at AS. So while I haven't taken the full A level yet, I do have a similarly heavy workload and busy schedule.
If you are a motivated person who can manage their time properly and do the work, I imagine you'll be absolutely fine! But if you find you're struggling, please just drop one, keeping 4 on is not worth it if it means sacrificing a grade in a subject or something. Good luck! I hope it goes well for you 😊