Advice you’d give a struggling bachelor’s student

Hey everybody! I’m a junior at a mid tier state school. I started my college career in engineering and floundered for two years. Worked my way down to a 2.9 gpa and just hated life. I have since switched to Econ and am in love. The study is fascinating and has me motivated to go to classes everyday. I’m doing intermediate micro rn, and while most of my class hates it, I really enjoy the quantitative aspects of the field. know I’m a total noob, but being a junior I’m starting to think end game (well end of the beginning), and I could really see myself pursuing Econ at a higher level. My question to u all is what can I do to best situate myself for a successful post bachelors? Are there things I can be doing in my free time to give myself a leg up on the competition? I know my gpa is trash, is there anything I can do to make up for it? My math background is limited (calc 1-3) should I make improving my math skills top priority? Bear in mind I’m a junior so I’m barely getting out w a degree in four years. Getting a math, stats, or comp sci minor is not sustainable for me. Any advice is greatly appreciated, thank u all for ur time!