Apply for whichever one you can see yourself enjoying more. If you are struggling to decide, write 2 personal statements and apply for both- make your decision once you receive offers. More people have been applying for pharmacy in recent years so of course this will have implications for employability and pay somewhat, but pharmacy may be a good option for you if you’re looking for something flexible. I can’t say much about optometry, but a lot of people did recommend it to me- including a pharmacist. It all depends on what you want to do.
You mentioned getting a B in chem- I’m not sure how other universities do it but it might be worth mentioning that there’s a lot of chemistry involved in pharmacy, so if you don’t like chem don’t be under the impression that it stops at A level.
Hope this helps