One other thing...going down to 600 grit is fairly pointless as a means of removing tool marks. Understandably, your tool technique cannot be good enough at this stage to get perfect results and we all had to accept a degree of poor finish when we first started, but if you have tool marks and slight grain tear-out that you're not yet capable of tooling away, then you concentrate on the 120 grit, not by going down to 600. Keep working with the lower grit numbers until you're happier with the result, before you move on to a higher grit number...and get some first hand help, it could be tuition, it could be from a woodturning club or from a mentor - it's worth its weight in gold!
Keep at it....it will come! Les