I have a question about the legality of and minors in New Jersey.?

I have this girl who really likes me and I really like her, I just turned 18 and she's turning 16, meaning she is 15 now. I have heard mixed answers such as "Once your 18 you can't have with anyone who isn't 18+" or "The consentual age is 16 in New Jersey so once she is 16 it will be legal" or "Once your an adult you cannot have with someone who is more then 4 years younger then you." Meaning I can legally have sx with a 14 year old? This is all very confusing and I'd like to be able to make an adult decision because she seems like she want to.