Overstayer IS96 : British Son & Girlfriend Pls Help

Please Help/ advise. form IS.96
I have a British born son and a british girlfriend which I live seperately from them.I was stop by the police in september 2015 Detained by the immigration because I have overstayed my visa. My claim were rejected because i am not living with my son and baby mother but i have enough proof of address bills on my name that prove that we live together and my name is also on the birth certificate. MAYBE BECAUSE I WAS REJECTED BECAUSE IT WAS A FREE WIAVER APPLICATION WHEN YOU ARE PICK UP BY THE IMMIGRATION.we are together FOR NEARLY FOUR YEARS. I was in detention camp for two weeks.I went to court got released and i was asked to be reporting every two weeks and giving a letter to be to be staying with my girlfriend ever since(got bail to my gf house). last two weeks at the police station when i reported last I was asked to come again on the 8th of December. shocking news today i received a letter NOTICE TO AN OFFENDER WHO HAS FAILED TO REPORT AS REQUIRED.
In the form they put i am liable to detention by failing to report as required and render myself to prosecution under immigration act for six month and face a fine of £5000.

The police officer told me a wrong date to report. APPARENTLY I AM SUPPOSE TO REPORT ON THE 1ST DECEMBER BUT THE POLICE ASKED ME TO REPORT ON THE 8TH DECEMBER AND I GOT THE LETTER TODAY THAT I AM GOING TO BE DETAINED NOT SURE IF THIS GOING TO HAPPEN BUT SCARED OF WHAT MIGHT BE.

What is your immigration history?

You say "I have a British born son and a british girlfriend which I live seperately from them" and then you say that you have evidence of living at the same address. Which is it?