Just keep practicing. I had that feeling for the last few months (Same exact things, 35/6 M and English and screwed up on R and S). Yesterday took a test and got 35 and 36 on reading and science. Just keep taking these practice tests. Few personal tips that might help:

Reading- for me, i was so slow/innacurate on the first passage. So I do 2,3,4 passages first, race through them, and usually have more time (~10 min) and less pressure with the first passage. This method has helped me on reading.

Science- just pure repetition, you will start to extract the info from graphs so quickly that time will no longer be an issue, science topics do overlap so that helps too. Science you really just need to maintain focus and practice. Science is a section that I think usually gets a boost on test day because you will be so locked in.

Most importantly, you have to REALLY want in mentally. You need to be locked in all the time. There's no skill holding you back in these sections, just keep working at it, it will come.

PS: once your R &S scores start to increase don't forget to stay strong on the other sections so they don't start to slide, because that happens sometimes no matter how confident you may be in those sections.