The whole mix is "breathing" probably from a compressor on master bus .. take a closer look .. overall is a very good try .. everything comes with practice and reading and keep trying
Try to calibrate your monitors so you know you take the best you can out of them and compare your mixes with reference tracks ALL THE TIME .. also take breaks during your session every 15-20 minutes .. trust me, if you keep mixing constantly for hours with no break the result will be a trash
Try to calibrate your monitors so you know you take the best you can out of them and compare your mixes with reference tracks ALL THE TIME .. also take breaks during your session every 15-20 minutes .. trust me, if you keep mixing constantly for hours with no break the result will be a trash