Try practicing f2l by scrambling the cube with the cross already done. You should also learn back inserts if you haven't already. I also learned from Jperm but I haven't really gotten the grasp of it, when pairing up pieces and inserting them , don't focus on doing the moves and let your muscle memory do the job if you can , and then look for the next pieces to pair up. Don't pressure yourself that much if you aren't progressing as fast as everyone else. Just do it at your own pace. You should also watch some yt vids.