K B:
Thanks for your input. Ill take another look at MCTB.
There are a lot of similarities there, but differences as well.
Pay attention to the description of the shifts from one jhana to the next and the differences between them. I think that would be the most helpful for you.
K B:
One of the core questions here is, how to differentiate beween jhana and non-jhana states? For example, take bliss. Is it possible to have very strong bliss experiences without being in jhana? What about boundless space and boundless consciousness?
You could try reading about the jhana factors (directed thought, sustained thought, rapture, happiness and single pointedness of mind) and then see if those factors exist in your own experience. However, keep in mind that the topic is actually more complicated than just those 5 factors and different teachers define jhana differently making it hard to nail down exactly what is and isn't jhana.
It is quite possible to experience bliss and/or rapture outside of jhana state. Bliss can be brought about by calming and stilling the mind and so can be experienced on the way to jhana. MCTB says it's also common to experience bliss during A&P events. I don't really know about boundless space and consciousness.
K B:
What about being in a absorbed state with basically little to no thought or sense of self?
When the mind is still, it can be much easier to see phenomenon (including thoughts) simply arising and passing away with very little attachment. This can give one insight into no-self.
K B:
The books say that there are an "endless" variety of possible states and experiences, and they also say there is both hard and soft jhana, so how does one distinguish between soft jhana and what I describe?
I believe the usual distinction between hard and soft jhana is the level of absorption. In hard jhana (usually taught by teachers who follow the Visuddhimagga) there is no discursive thought, no awareness of the body, etc.. In soft jhana (taught by those who follow the suttas' description of jhana) there can be some thought, there is some awareness of body and phenomenon outside of the object. It is actually possible to do some insight work (3 characteristics style) while in soft jhana. This would not be possible in hard jhana and insight practice is left for after exiting jhana.
K B:
I could be wrong, but I don't think I even have access concentration, have not experienced the learning sign and counterpart sign etc.
Access concentration is another tricky subject. I've seen several different definitions that don't quite agree with each other. As for the Nimitta (counterpart sign), I've learned that most people do not actually experience a visual Nimitta when doing breath meditation so it quite possible that you would achieve deep concentration without experiencing a light. Check out this article: http://www.arrowriver.ca/dhamma/nimitta.html it could be helpful to you.
I just took another look at your initial post and I would hazard a guess that somewhere inside "You focus and dwell on this texture for a while as it gains in intensity and then "pops" into a new texture." are hiding both your learning sign and counterpart sign.
If I may ask, what is your goal with this practice?