I do not think I am the most qualified individual to answer this as I am not studying any of your mentioned interests at a university level. However, I am a fellow IB student who takes Maths and Econ. HL and have spoken to my economics teacher on numerous occasions about the level of Maths in economics.
Essentially, IB Economics avoids any sort of advanced Maths, such as calculus. In university, from what I can tell, calculus will be used abundantly. For instance when calculating the lowest point of Average Cost for a monopolistic market. Nonetheless, I doubt taking SL maths would hinder your study of economics at university as this level of maths will be taught there and is not even remotely needed for IB economics-level maths.
Regarding your chances of being accepted at a course for Economics, Environmental Studies or Geography, as long as you achieve the subject and grade requirements of the universities, should be fine. Also, not to generalise, but those three subjects also have quite a bit of overlap in terms of content. Hence, universities would be able to see that you have a keen interest in that subject area.
Either way, whatever you decide to do in the future, I wish you the best of luck and stay strong during the IB, it can be soul-crushing at times, but always keep the end goal in sight!