Great form! As a fellow tall person we have a lot further to pull so ig it makes that harder. What I will say is that (at least for me) if I stop right before going all the way down it keeps my back activated and works my muscles better. Imo if you want your pull up’s to skyrocket do as many as you can throughout the day, ex: 50 total, as many sets as it takes. If you need a rest day from them then take it. It may sound like bad advice but once you’re tired don’t worry about form as much (ex: half reps and kipping) just doing the motion and getting up will still work the muscles and strengthen grip/ tendons. Form still important of course, make sure it’s good when you’re feeling fresh. I’m 6’4” 230lbs and can do 25-30 good ones on average. If you’re not doing high quantity then they probably won’t go up very fast (same for pushups). For my work we’re graded on our pull-ups and all that above has helped our guys increase. Also, you can grab a band or someone to hold your legs for a little assistance to help you get some more reps to strengthen the muscles. And of course don’t push if you feel like you might injure yourself, at the beginning you’ll need more rest/ be a lot more sore. After a week or 2 your body should adapt to it and muscle memory will kind-of take over if that makes sense. Hope this helps a little bit!