I also did IGCSE and GCSEs like you, got 5A* 4A 3B 1C. I've completed my IB this year and was looking at Medicine in the beginning. I also had the same issue as you - didn't know whether to take IB or A levels. IB was hard for me since I didn't manage to perform well and even though I received a predicted of 39 points, it wasn't enough for universities. Especially due to the fact that I applied to the UK as an international student and that I did Maths Studies instead of Maths SL or Hl (HL is definitely preferred). However, I pushed through even though I was also struggling in HL Chem and Bio.. BUUT, when I applied to Singapore (my home country), I applied for courses like Business, Law, Architecture, Accountacy (mainly those whose entry requirement didn't require Maths much or at all - TAKE SL MATHS or HL but maths studies seriously restricts your options...) at prestigious universities like top 15 in the world and I GOT SHORTLISTED for Law and Architecture which was so surprising!!!! This would be one of the benefits of the IB, to be able to branch out if a certain course doesn't work in your favor I guess
Plus, tbh, if you reallly study during the two years, it's not that hard and can be pretty fun too! SO, that;s my story.
Personally, I would say take the IB if your grades are pretty strong at GCSEs and if you are able to cope with the languages and maths bit. I would say that languages and maths and are the toughest in the IB course. Then comes both CHemistry and Physics and then that's it. Take ab initio languages if you're able to - it will be a lifesaver, believe me. Stick with that ab initio Spanish!
If it helps, I also took the exact same subjects as you chose but Spanish B (it's not even a "B" language, you practically have to be fluent in it to get higher than 5 hahhaha - I'm so nervous for results day) and Maths studies. It was my first time taking psychology and even at HL, it was pretty okay and easy to understand
A levels wise.... I guess you do have less of a workload but if you don't get your grades, that's it. You can't apply for other courses. AND A Levels are ONLY beneficial for Medicine IF you're applying to UK... If you're looking at university courses all over the world, the IB is definiteeelyy better - unis prefer this. For NZ and Australia applications, you just need to pass the IB diploma (mostly) and then do one year of Health Science and then take the UMAT for Medicine.
Definitely do a looot of research into the unis that you want to get into because certain unis are in favour of either A levels or IB. But yeah, uni research can be really tedious too. Email them if you're not sure. I think Bath in UK really understands how hard the IB can be and also favours IB students more due to the skills learnt in the long run. For UK, there's also a new uni for Medicine called "UCLAN" and entry requirements is 34/35 points I think? It's a separate application from UCAS meaning that you can apply to those 4 unis in UCAS and then also apply to UCLAN meaning that you
actually apply to 5 Medicine courses! Ha!
So, if you do need any more tips or help or questions, just hmu . Hope this was helpful!!!