I haven't been in exactly the same situations, but I've had D/s relationships (well, not that many) and a LDR...so I hope my two cents qualify nonetheless

Firstly, I don't think that you come off as "needy" when you want to have some more contact with a person you're in love with...no communication over 3-4 days sounds awful to me. I'd be so very insecure on day 2 that I'd be running in circles. I really understand how hard this is, and I presume that it is even harder in a D/s context when you are still in the "settling in in the respective roles" process.

As far as insecurities are concerned...I guess it's perfectly normal to have them. I still get insecurity flashes now and then, especially when I take another step deeper into the lifestyle...then I'm suddenly thinking "am I becoming too submissive? Now, he can't possibly like that, can he?" It's probably the cultural conditioning that gets in the way, though -- if they didn't like you doing it, why would they make you do it? Not every guy is out to prepare traps for you.

What always helped me was hearing that it didn't make me less desirable, less loveable -- actually, quite the opposite. Or try looking at it from a different perspective: you don't respect or love him less because he's dominant, right? In fact, it's one more thing that fits perfectly -- so why would he think differently?

I believe that relationships take time to grow, and D/s relationships take even more time because they are more intense (that's at least my opinion). So the best advice I can probably give is to take things slow and one step at a time. Don't do anything you're uncomfortable with. And communicate, communicate, communicate. I know this doesn't fill the gaps...but I am convinced that it will eventually overcome the insecurities etc.

From my LDR experience...this is vanilla, but might help nonetheless: Agree on a time when you both can take 5 minutes to think of each other. Alternatively, masturbate together at a certain time -- not as good as the real thing, but still nice to know that the other one is doing it as well. If the little tasks naomisagoodgirl suggested are your thing, I'd talk to him about it. Me? I really like that, and it helps me feel closer to my guy in busy times. Umm, there are things like read the same book and talk about it, or watch a movie together, or send a text message now and then...but I don't know if that's of any use to you. I'll stop rambling now