Twirling, I'm sorry...but this is going to end in tears. Long distance is tough at the best of times, but mix in the age differenc, your level of insecurity and neediness and it's not surprising that it's all going pear shaped for you.
I think the two of you really need to make a decision NOW on the kids issue. If she wants kids in 10-15 years time, are you up for that? Yes or No? If you don't want kids in 10 or 15 years, you may as well just end it now and find someone who's compatible with you. Leaving such important decisions in the air will only add to your level of anxiety.
I also have to say that you you feeling deflated, rejected and upset if she's out of contact for a mere 12-19 hours is downright alarming. Mate, if you can't trust that she still loves you and cares for you when you're out of contact for less than a day, either you or the relationship has big problems.
Time for you to do some serious navel gazing about this.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.