IhaveAA.AAdoesnothaveme,
I'm sorry to hear about your transplant delay but July will be here before you know it.
I'll tell you about our experience at a hospital in California and hope it's somewhat the same for you. Isolation may sound scary but isn't like solitary confinement in prison (although the institutional food might be no better
). You aren't really all alone. Nurses and doctors will still be in and out. Visitors may be allowed as long as they first "scrub" (like a doctor going into surgery): wash their hands with a scrubby brush and put on a cap, mask, and maybe booties or a surgical gown. The idea is to save your life by preventing you from getting an infection while your immune system is being rebuilt, so it's well worth the trouble, and if the hospital staff doesn't enforce it then you certainly should.
When people aren't there in person there's also Skype, as you mention, and IM and SMS and Twitter and other social networking sites. If you're like most young people I know then you're connected with friends, including your boyfriend, whether or not they are there in person!
You might miss your nephew but it's only temporary, and kids that age don't have a good sense of time. If you say hi in videochat now and then he'll probably be happy to see you that way. And if he gets a toy "from you" (which you can arrange with your family ahead of time) so much the better.
Hospital rules are necessary but they are designed to benefit patients. I don't know what the rules are about people staying the night, but if it's supposed to be an adult then I'd guess that your sister qualifies.
There are two reasons to have family members around. One is because they are your support team and keep your spirits up and your life closer to normal. The other is very practical: they can help take notes and keep records, talk to the doctors with you, be your "spokesperson", and help you if there are decisions to make about your treatment.
When my wife was in isolation, visits from family members, even some who merely waved through the glass, were a welcome dose of good cheer. Your nephew could probably be brought by to wave at you that way, if seeing you "looking sick" wouldn't be too scary.
People didn't have to visit every single day or stay for very long. It was knowing they were there for her that gave my wife the boost. Nobody was allowed to send her flowers, food, or stuffed animals, but people sent her notes, photos, or picture postcards that she put on a bulletin board, and that was another nice way to keep friends in mind.
You may not always feel like having visitors. When you don't, don't be shy about telling people it's a bad time. Anybody who cares about you will understand and not be offended. Like you, they'll know it's temporary and that what's important is that you get better.