There isn't half some crap talked on this forum sometimes. People who haven't actually studied an Economics degree (that includes you, A level students) come giving advice about stuff they don't actually know about.
To claim you 'know what you're talking about' about an economics degree you should be able to go through a full undergraduate micro textbook like Varian, Perloff, Katz & Rosen etc and understand all the topics in there, and a full macro textbook like Mankiw, Blanchard, Burda & Wyplosz and understand all the topics in there. Economics graduates will have done other topics as well depending on what they have specialised in, but what will be common to both is that micro and macro, which is pretty standard wherever you go because it is taught from standardised texts that are used in the US and here.
People who have studied business, management type degrees with some economics in it might have done some theory of the firm but they haven't studied economics properly.
I find A level covers only a small part of micro and although they cover quite a lot of macro topics, they don't really go in to them properly, A level is a discussion based course, you don't really need to understand much theory. I don't know whats on the IB curriculum but I doubt it is taught in a 'university format' - does the micro do preferences, indifference curves, the first/second theorems of welfare economics, and teach you to do 2x2x2 diagrams to analyse markets in general equilibrium as well as partial? If it doesn't do that then it's not university format because those are the basic principles on which university micro is based. University micro is stuff like choice under uncertainty, intertemporal choice, asymmetric information, principal agent contracts, factor markets - if the IB is faffing around with MR=MC stuff then its not university format.
Similarly with macro, does the IB cover equilibrium in the labour market, does it do the ISLM model? Does it do the money supply-money demand model? It probably covers the Phillips Curve but do you use a Phillips Curve equation and combine that with Okun's law and the AD relation equation to be able to solve problems looking at how nominal money growth influences unemployment and inflaton? Does it do growth models like the Harrod-Domar and Solow models? When you do open economy stuff do you use the uncovered interest parity condition and Marshall Lerner condition? I am not picking advanced topics to make it sound hard - these are all the bog standard bricks and mortar of macro, all the economics undergraduates on here will know what I am talking about.
So basically if you have just looked at that list and thought....hmm wtf are those....then you haven't done a course which is equivalent to university level economics.