If that were me, I would want full disclosure of her entire financial situation (the fact that she claims not to know usually means it's worse than they think). You sound intelligent enough to be able to help her get out of the mess she's in - which she doesn't seem willing or able to do herself. Moving forward, as you seem to be financially "unequal" you will need decide how much of a "hit" you are prepared to take in terms of her financial contribution to the relationship - this will presumably be fluid until her situation improves. Otherwise, unless you live an incredibly "quite" life you are going to have constant issues with holidays, meals and days out, Christmas and birthdays etc.
Consider charging her the marginal extra costs (25% council tax, a few quid for gas and electric etc) in the short term and ramp this up as her income improves.
From experience, living with the financially inept can be miserable - take control and get it sorted.