Currently I have been using these DIY pill capsules that your talking about which I bought from eBay but I didn't really notice any good growth! I have been using these tabs with this plant and it's not making any difference feels like those are useless!
Which one would you say are the best tabs you have used out of them all?
I know it feels like I'm wasting money buying all these difference plants and then they end up not growing :/
Have you tried Java Fern? Low light plant and doesn't need substrate tabs specifically. Another might be as floating plants eg water sprite
http://aquariumtidings.com/java-fern/
I'd buy API tabs again. I try to get ones with a dark clay as these should have a better cation exchange capacity (cec) but any clay is better than gravel. If you can pull one stem plant out and no roots are developing I'd consider it a lost cause.
https://en.m.wikipedia.org/wiki/Cation-exchange_capacity
On the good news front you have no algae.
I couldn't find your light? Is it a white light, standard display led light or something more fancy? How deep is the tank and how long are you running lights for?
If the shrimp are ok with the liquid carbon, I'd try dosing that as well as mentioned above. Trying to get a better balance of lights, ferts and carbon source.