40 somethings and relationships

My gf and I got together just 5 months ago and fell in love very quickly. I'm 45, she is 40. Each time we got together it just got better and better and inevitably it couldnt forever constantly keep going that way. A few weeks ago i got in a 'huff' about something and made her feel bad by going quiet. I didn't mean to, my brain just shut off and when I tried to explain I made it sound worse than it was. Since then we've talked and are still together but i'm aching for it to be how it was. Because we live a 40 minute drive from each other and because of awkward work shifts in the early weeks the only issue we had was not seeing enough of each other so strived to see each other at every available opportunity. Since my 'huff' of a few weeks ago and the subsequant discussions it seems that that was becoming too much, with me occupying all of her all to little free time. So we've stepped back a little but I'm struggling to not over obsess about her. I really love this woman. She's on my mind every second. I over analyse every message between us and worry that her responses are not as 'loved up' as they were. For the first time ever i've become the 'needy' one in a relationship and its crushing me inside. I knew things would have to even off a bit as we were like lovesick teenagers but I'm finding this hard to handle. Both of us had been single for a while and are both quite fussy and neither of us expected to fall in love quite so hard as we did. I feel like in that moment I made being in a relationship seem like a hassle, where previously it had all been so easy. How do others cope as relationships change from those first 'heady' months? I'm madly head over heals in love with this woman and I'm in danger of my obsession with her becoming too intense.

Not exactly what I've put here as I'm afraid of coming on too strong while she needs us to find the right balance. She is a little quieter message wise but perhaps always was and it was me making the big statements. How she feels is all I'm concerned about. Seeing her tonight and hoping to talk a few things through and find that out. Thanks for your input.