14years overstayer with 2years unmarried partner application

If anyone could help

He came here when he was 16years old and he's now 31 next month(overstayed) ... He does not have criminal records or asked to leave the united kingdom in spite the previous applications(unsuccessful marriage to eu citizen/a father of a British child. That the DNA showed the baby wasn't his) he has made to the homeoffice.. Yes we are intending to get married and five months ago I was pregnant with twins for him but I had miscarriaged and bcos of my recent op. Even if I have another pregnancy, there is every possibility I will lose it.. We are both living together at the moment.. We been together for almost 18months but we have some proved to show our living together for 13 months or so.. The reasons why we are concerned is because my uncle said the years he has overstayed in England could be against him if we have to submit applications for unmarried partner visa.. Any assistance / help will be appreciated..

The requirement for unmarried partner visa is 24 months relationship akin to marriage which in your case cant be fulfilled and moreover for switching in to this category the applicant must have valid visa. Easiest might be by applying spouse visa by marrying from outside the UK but still in that case his heavy period of overstaying might cause severe delays or the outcome of the application.

Thank you for the quick reply
Ok this Is my immigration history. .
I came here when I was almost 17 with visiting visa hoping when I get over here.. The family would enrolled me for college.. Since they both British and the wife is my sister.. As time passed by.. The couple broke up. As a result of broken relationship, I was unable to enrol for college because my sister did not know what to do at that time... When I was 25 I met my ex who is Portuguese and we put in an application for E. U family member.. We was unsuccessful and we both went for the appeal.. As the judge said.. There was too much mistakes in the application and I was asked to put in next application.. In the process of that her mummy passed away back in their home country Lisbon, Portugal and she moved back to Portugal and she never come back.. So two years later I met my ex.. she had a child thinking the child was mine.. So we put in an application for flr-fp after the 4th months the homeoffice asked for additional proves.. Which was DNA.. We did the DNA and I find out the child wasn't mine so we couldn't send it base on argument and the relationship broke down.. The application was refused and i was giving in country appeal.. Since the relationship broke up., i couldnt get help from her and i moved on.now I am with my newest girlfriend.. We have been together for 18month and she knew my immigration history.. So 6month into our relationship .. Se asked me to moved in.. And she added my names on every bills in the house as second account holder.. My question is this.. Even if we meet the 2years unmarried partner application.. Can we submit it on flr-fp or flr-m.. What options will be the best option for us please ?
We meet every other requirement except for the months.. She work as a nurse with extra shift and huge savings the thing is that we both scared to leave UK to put in an application.. If anyone could help please