Why am I still so insecure and Paranoid?

I've been going out with this girl for almost 2 months. I'm 20 years old but she's my first girlfriend. I like her alot and she certainly seems to feel the same way about me but for some reason even after 2 months I still feel nervous. When I'm with her its usually not so bad, but when we aren't together, I start to worry. Thoughts like ''I won't be able to think of anything interesting to say" or "I'm not funny enough" constantly run through my head. Strangely, although I've never felt like the most socially capable person, she has never given me any reason to believe that the way I act bothers her. Despite this, I can't seem to shake my insecurity.

What I really want is to just feel confident in my ability to interact and engage with her. My sense is that if I could stop being so worried that I'm not interesting enough, I could open up and ultimately end up being more interesting.

Any suggestions?

By the time I was your age, I had five years of dating experience. Of course you're nervous- it's all still pretty new to you. Don't worry about feeling insecure- it's just making it worse.

Agree with above. I felt this way with my first girlfriend, too. Luckily for me, I was a lot younger, so got through that by the time I got to be your age. Let yourself feel how you will feel. The sooner you get comfortable with your own feelings, the sooner you'll feel comfortable around her. Considering she hasn't gone running for the hills yet, you must be doing someone right. Attach yourself to that reality.

Like you said, because it's your first girlfriend, the whole dating world is new to you, and it's natural for us to be apprehensive and anxious about all things new and unknown to us. Give it time, am sure you are doing a-okay, try not to be in complete of awe of her, and don't be too try-hard with impressing her either, just be yourself, that usually does the trick.