I believe in you, just put a lot of effort in right now and you can achieve. Just know, you can do a LOT of things with a TAFE diploma and even transfer into uni programs. Also, you might be a hands on learner or tertiary education might not be your thing, you might want to venture on your own and discover things yourself, if thats the case try looking into finance and being an entrepreneur and starting your own business. Best of luck and most importantly, do NOT give up; everyone has different strengths and weaknesses and there’s no reason to bash yourself for any shortcomings!