hey pink penguin,
my h2b is in the marines and since we got engaged in August, has been out of the country for 4 and a half months

He had two weeks back at home over Christmas but that was spent visiting family etc. We are getting married in May this year (EEEK) and I can totally empathise with how you are feeling!
It's surprising how many people are going through the same, but I have felt quite alone even though my parents and MOH have been amazing.
I would say try and keep positive, think that the final result is that he will have a great career and you will be husband and wife. Try and keep busy with a mixture of wedding and non wedding stuff - You are still a girl, not just a future bride. That's what I had to keep remembering!!!!
Another thing that always helps me is to write to my H2B, a bluey (do you have them in the RAF?) or an email every day or so acts a bit like a diary and really helps you cope with stuff.
Hope that helps you a bit. Keep smiling