EEA family permit

[co_ach]

hi everybody,
i would like someone to advise me on eea family permit. am a nigerian and i have been living with ma patner who is a slovakian for the past two years. we are planning to go down to nigeria and get married but the problem is that she is scared that i might not get my permit since i overstayed my visit cos i came to this country on a visitors visa. please i would need your advice to know how to go about things out here.my girl is excersinig her treaty rights.urgent reply needed and also the things i would need to make my application.