Am I allowed to say homesick?

Of my friends, as they've come and gone, I've always been the one to stay close to home. Before this year I thought moving to Atlanta, a mere four hours away from Columbia, SC, would be too far to move to work after graduation. When I was younger I would cry and cry during sleepovers because I wanted to go home. To say that hasn't changed much for most of my life would be an understatement.

But now, after taking such a huge risk in going to London for five months, all I find myself thinking of is London. I research job openings (and their teeny salaries), apartments, and companies that I'd like to be a part of. I scour the interwebs for UK companies that will take someone from the US, as opposed to someone from the UK, considering VISA applications are so difficult to get. I feel out of place in Columbia.

My question, for those of you who have studied abroad and who haven't, am I allowed to say I'm homesick? Sometimes I feel so dumb saying that I lived in London since it was only five months. So could it really have ever been home? When I first arrived I pretty much spent the first three days crying my eyes out because I missed home. But now? I feel a bit like a fish out of water.