I am no expert when it comes to PE (yet) but I have been fairly successful so far - manual stretching, I’m 1.2 cm longer (erect) today than I was two months ago - and about 2.5 cm longer BPFSL.
IMO - which, as I mentioned above, is a very inexperienced one, so take it with a pinch of salt - you are doing way too much too soon. I agree with Jumbojim that you need to take some time off to decondition. If I were you, I would do the following: take a month off from EVERYTHING PE-related. Then commit to three months of consistent manual stretching, starting timidly and working your way up. After three months, reevaluate things. Don’t bother measuring prior to this - give your body time to react without working yourself up about it - you may legitimately be a slow gainer.
When I go to bed, I read my kindle with one hand, and with the other hand, I stretch my dick out. I started just stretching it up my body - holding it below the glans, and positioning the glans at my belly button. This is enough that I felt a good stretch at the base (ligs) and later, in the shaft (tunica) - but not so much that it was painful. You should prepare for occasional discomfort, but not sharp pain. It is ok if your dick feels a bit “weary” or “beaten up” after the event, and a little post-pulling shrinkage is fine too. But prolonged loss of function (ED), prolonged loss of size, and significant pain are all signs you’ve gone too far.
I started just pulling up like that and holding it for about 15 minutes - maybe breaking every couple of minutes to kind of flop it around and give it a couple of seconds of massage. Then I started adding more time and different directions. I now stretch in each of the cardinal directions (up, down, left, right) for 30 minutes every night and 30 minutes every morning. I do this five days a week then take weekends off. I think consistency, and starting small and simple, are what have worked in my favour.
Good luck!