Weak rubbery stems, slow bud development. Ideas to help recover or increase growth?

Sad to say, those are some poor looking genetics there and I doubt they will ever produce anything much good. I too would be starting again and definitely not with seeds from this breeder either, if this is their level of "acceptable breeding standards". After 7 weeks in flower, they should be big chunky buds nearing maturity, not wispy, thin undeveloped stalks. I would also consider contacting the breeder and questioning them as to whether they think this is an acceptable example of their products. It may be a problem they are aware of and they might offer you some sort of recompense, but they may also just blame you saying you did this/that wrong blah blah blah and that they only sell their seeds for collection purposes and you are naughty for growing them. For my recommendation, I would suggest trying Sweet Seeds seeds, they have awesome stable genetics and after trying nearly every strain they have, I can honestly say they don't have any duds either. After growing for 35+ years, they have become my "go to" breeder, with plants that are simple to grow, potent, productive and with highly refined genetics. Even a monkey could harvest quality buds without trying! A highly under rated breeder in my opinion. And yeah, buying the best quality soil mix you can afford is the only way to go, you can't grow prime plants in dirt. Besides, the soil is the overall cheapest part of any grow. For some really good tips on growing plants in containers with soil, check out the "Mandala Seeds" website. On their main page click on "grow guide" and there is a wealth of great general growing information that applies to all cannabis, not just their strains, including soil brands that are suitable and available in both the U.S. and Europe. Also good information about nutrition and fertilizers. They have been awarded "Strain of the Year" a couple of times by High Times, so they certainly know their stuff! Highly recommended reading for everyone. Hope this helps, Organoman.

Hey, looks to me like to much N in flower, leaves clawing and very green, hope this helps, all the best 👍

Looks like you need to get your tent in order. Need to control the area. From the root zone to the top of the plants. Good thing with a diary you can learn from all the mistakes.

I looked at your other pics, the soil looks very suspect. I see way too much wood chips and trash in the soil. I'd guarantee that's your problem. You could get some really good organic and perlite mix and try to transplant, but it's probably too far gone. I'd bet the herm at this point. The one area you can't skimp in if your going soil, is using a good mix. The best seeds will never do well in a poor drainage high ph soil. What I'm seeing in the pot and the results is one I've done a long time ago.