My only word of caution is that you need to check with individual Medical Schools that they will accept your extenuating circumstances, as although you have not resat, you have taken 3 years to complete your A levels and most of them specify that they must be completed in 2 years unless you have extenuating circumstances.
If you really want to do Medicine, then I would advise applying this year, rather than waiting and applying for GEM, as it is much more competitive and not even certain to still exist in 4 years time. As stated, most Med Schools will not accept people who drop out part way through another course, and this will also mess up your funding. Another year in the grand scheme of the rest of your life is not a lot. Good luck