To be frank you are making a big deal out of nothing, I used to worry about these things before soon realising that flying is not about mental arithmetic or supreme hand/eye co-ordination (unless you fancy flying the Red Bull Air Race for a living of course). It is about dedication, perserverence, ability to study effectively, discipline/attitude, mental awareness and workload management.
Studying for your ATPL groundschool and doing your IR will certainly test your resolve for being a professional pilot...
If you are already into your PPL and you're not falling behind the syllabus you have sufficient inherent physical/mental ability to be a pilot. If you are aiming for an airline position, bear in mind airlines look for team players and effectively "flight managers" to crew their flight decks.....