How do I come out to my bf without him leaving?

Hi I'm a 14 years old. I'm not sure whether really I'm a guy or a girl. I present myself as a girl tho. My bf says he's straight. We've dated all summer. I look like a girl I have a syndrome called klinefelter's syndrome that makes me have feminine qualities and grow bigger breasts and wider hips so to speak. So I can pass alright. So I've not told him but we've become more intimate lately and I want to make love soon in the future and I like don't know how to explain this though. I mean I worry if he finds out he'll leave me and I also worry if he stayed he'd see me as just another guy. What should I do

If he 'leaves' you then he isn't for you, so don't worry about that aspect of it.

Just make sure if/when you tell him that you're in a safe place, like at home. Some guys, the insular type, don't take too well to information like what you're proposing to reveal. He might consider you having lied to him if you guys have been intimate already, with him thinking you're a biological female that is. People can 'change' when it comes to sexuality.

but the hardest thing is to tell someone and explaining to them it when I never have really tolf my whole situation.

You may indeed find it hard. Not debating that aspect of it.

But you need to be smart about it though. Ask yourself how open-minded your BF is and how he'd likely take such news. Personally, I could appreciate the awkwardness in revealing something like what you're wanting to and would sympathize. But many males don't see it this way and just jump to their default instinctual mechinism - anger.

If you don't trust the guy enough to tell him (which may be the case given you're coming here first) then you need to ask yourself if he'd accept the 'real' you if you're honest with him anyway.

You know him, I don't. Just be smart about it and temper your heart with your brain.

I know I think he might but I think if I presented like that I was born with a condition and left out the fact that I was raised male he'd take it better but then I'll feel like I still am lieing and how long could I keep up with that?

As your other responder said here , just be sure you are not alone in a situation where you cant get help if he reacts badly . 14 is a tough time of life for anyone , but as a father who also remembers how it was at your age , I think the sooner you are true to yourself and others you want to include include in your life , then you will be happier and find a true love sooner than later in life. Just be careful .