Brexit...

[inga-sharon]

Hello,
I have few questions and I really need a help.
I live in UK since 2014. I came to work as au - pair. Unfortunately I had just pocket money and it means the job was not legal. And of course they will not count me as exercising treaty rights.
I applied for JSA at the end of 2014 and I have been rewarded for 6 months of JSA.
Later I continued as an au - pair for few months again.
I started legally work since 2016. But I have gaps in my working history. I applied for other certain benefits, but I failed few times HABITUAL RESIDENCY TEST.
I have mental illness and I am on medication. There were period, when I couldn't work. I don't think they will count me like exercising treaty rights again.
Now I am in part time employment since 2017. Also I am part time student. Unfortunately without CSI. Does it mean they can count me as exercising treaty rights only from 2017? So, it mean I would be able to apply for permanent residency only at 2022?
Will they allow me to stay after cut off day or will they deport me.
I really want to stay here forever, but do I have any chance?
Thank you for your answers.