Girl or Boy?? Confused..?

I'm currently 17 weeks pregnant & yesterday I went in for a scan because I had some mild cramps and of course panicked and ran to the ER. THe guy that did my scan said do you kno what you are having? I said no, but of course was open to finding out. He said well it looks like a boy!! I looked on the screen and sure enough there was what looked like a little ..He then said, well look at this. He backed the probe back a little bit and said do you see those 3 white lines?? I looked and sure enough there they were!! They were right behind the thing that looked like a and didn't expand onto the .. He said I would for sure be able to tell in 2-3 weeks.. I am really confused because I know they say that it is possible for the cord to be in between the legs, but how often does this happen?! Would the cord really look that similar to boy parts?? I just can't figure it out.. Any personal experience stories or opinions will be greatly appreciated.. Thanks :)