Elecro, from what you're saying you spend all of your time trying to get good grades, but the workload is so intense that you have terrible grades!!!
listen.
if you can't understand the work, google it. if that doesn't work, get a tutor, or ask your teacher. if your homework is so overbearing that you can't keep up then ask your teachers if you can work something out. communicate. you're not allowed to complain about your stuffty grades if you aren't trying.