Is it normal to still feel smothered in a long distance relationship?

My boyfriend and I have known each other online for around 5 years, so about a year and a half ago he came to my town to take me out. We found out when we met in person we got on better than expected, so decided to try a long distance relationship (even though I've found them difficult to maintain in the past).

We usually spend a few days/a week together every month. We're talking about finding somewhere to live together. We agree that it's difficult to progress our relationship living so far apart. We know it'll either make or break us but we've talked openly about it and agree it's worth taking the step.

However, the problem is that he is very insecure. For the first few months we would spend most of our time either talking online constantly or texting whenever we weren't at home. However this has dropped off a little over time. We do still communicate almost every day, but not the constant dialogue of a new couple.

For me, this is fine. I am independent, and though I care about him, I enjoy my own space. I accept that relationships lose the intensity of the early days and take on a more relaxed tone. I'm comfortable knowing that I will see him next week, or speak to him later, without having to know how he spent every minute of his day. To be honest, when we're apart I don't 'miss him' as such - I just get on with my life until our next visit.

But he's concerned that we "don't talk like we used to", and he wishes we could go back to constant communication, even though I've told him that I feel stifled by having to text him constantly.

If I happen to be busy I return to many messages from him along with criticism at my slow replies. He usually then tells me that he needs to have a 'Talk', and that it's important. These talks usually end up as a big outpouring of insecurity about how he thinks we're falling apart, and that I don't care because we haven't been speaking, when for me it's been something as simple as watching TV instead of spending the evening online. I reassure him that the commitment is still there, but I find myself getting increasingly annoyed that I need to keep telling him this - literally every few weeks.

It's now at the stage where I feel so trapped between either constantly texting him so that he knows I think of him or having to deal with him wondering why I can't maintain the same intensity. Sometimes I feel so smothered by him that I just tell him to leave me alone for some breathing room.

Things are usually much better when we're together, though he does have the annoying habit of constantly asking "are you okay?" to the point where I get irritated.

Part of me thinks that all of our problems are caused by distance, and that it exaggerates everything. If this is true then I think things will improve when we move in together.

I know that he has never really had a proper girlfriend before me, so perhaps he doesn't understand that relationships don't regain their intensity after the first year or so. I wonder if his insecurity is just that he's scared of losing what we've got - but I can't seem to make him understand that our commitment is enough for me. I don't need constant reassurance, so why does he? I've never been a hugely affectionate person (nobody in my family is) but the fact that I want him to move in with me and start a future with him should prove my dedication.

But part of me is scared that he can see something about me that I can't; that he is actually more committed to the relationship than I am. If I am so irritated by his constant need for affection and reassurance, it scares me that this means he is the wrong person for me. I've wondered if I would be as OTT with affection as he is if I met the 'right' person, though I've never really felt like I am that sort of girlfriend. But I don't think I would even be having these doubts if he didn't constantly question the state of our relationship!

So as it says; normal to feel smothered by this?