interview called

[iibdii]

hi everyone, would really appreciate any insight as doesn't have a clue whats going to happen here.

About me:
Came to UK in 2004 on study after completion applied for HSMP which was initially refused for a minor reason, reapplied after fulfilling requirement and waited 2 more years for decision and then it got rejected as well went through all the tribunals / JR took another 2 years but could not get the HSMP.
in 2009 i met my current gf while this was all on process i applied for COA for marriage in july 2010 for which they asked me proofs and pictures and documents etc and i sent them, i never heard from them after that, the COA scheme abolished a year later of applying. we were both then non living partners,

About Partner:
My Partner is dual national hold Irish & British passport, currently on medium rate Disability with some other benefits along with it, she got two kids from previous relationship which ended because of death of the partner

about Case: i applied for EEA2 non living partner in july 2013 and a month after that i moved with my partner so its been 4 months or so i am a living partner but i did not get work permission on my certificate of application as i believe you have to get married for that.
for proofs of relationship i have submitted pictures, dozens of travel tickets / phone bills / and original home office letter confirming i applied for the COA for marriage 3 years ago with the same partner.
after i moved the UKBA went to my previous address trying to find me which i believe was to detain me, but i was already in Northern Ireland so i missed them, Now my solicitor got the letter for interview for both of us to attend in liverpool

Concerns:
Can i ask them to held interview in Belfast as because of partners disability and kids school ?
(Did that and got reply Liverpool is only place where they can do interviews and please confirm if we are coming or not)

any chance of proving im un paid full time carer of my partner (doesn't even get carer allowance as i am subject to immigration control) and would it effect my application or it only works in Derivative right of residence application?
We got GP letter, Psychiatrist letter about mental health issues and inability to work because of panic attacks and very heavy dosage of medicines.

currently i am not making any money and savings almost depleted so if they force me to attend liverpool interview can i ask for travel expenses?

Partner Pregnant:
Partner got pregnant and the next scan date is just a day after interview i.e 22/01 we do not have any certificate etc to prove pregnancy because its less than 13 weeks yet,

we can not get married as they have my passport for last 4 years or so and dont want to invite whole family f my partner and then for them to come and disrupt wedding

please advice what are my options here.
any insight please