Hey!
WOuld you mind sharing which species you have extracted before and what where the results, even if negative?
I highly suggest you get some ehrlich reagent at least since it will tell you if there are indole-based substances, gives a great idea on what the content might be, specially togehter with TLC.
When you say you're not ending with anything recoverable, not even a goo? Sometimes goo is misleadingly heavy, seems like little but its plenty.. Also maybe 10g plant material might just not be enough for a decent yield.
Either way thanks a lot for sharing the info and making this research!