I'm assuming this is a girl you have either just met or don't know very well. Those deep conversations can be very good things for developing that hallowed emotional connection (google "deep rapport".) Deep rapport is obviously a PUA thing, but it's also something I think has merit - there was a study done by a psychologist whose name escapes me, but who determined that he could induce very strong emotional connections (some have used the word love) in 45 minutes with 36 questions.
The problem your having is with self disclosure. And the whole point of that man's study was that one of the foundational things a couple can do to develop a deep romantic connection is to participate in mutual self disclosure. Be careful here, because you don't want to give away the ending of the book to the girl before she's even had a chance to read it. She's probably asking you questions about yourself though because your directing the conversation around her, which is good, and if you are doing it right, she is probably realizing that you two are developing some type of bond and wants to find out more about yourself.
Why would you want to develop a bond with someone you don't know?
You need to calibrate what you say according to the tenor of the conversation. If you really are in the midst of something more serious, it's probably not the best time to go in to full out comedy mode. If you haven't already, you need to develop a sense of social acuity so you can understand intuitively what is sorts of actions will bring you closer to your social goals and what will bring you further away.
If it's towards the beginning of the conversation, I would be more playful, comedic, and less serious. If it's progressed to a more serious point where she's sharing something more intimate and personal, I wouldn't talk like I was on an episode of Oprah by any means, but I would calibrate accordingly. Surely there has to be something in your life you can talk about that reveals little nuggets of who you are without really saying a whole lot. And I've found that's really key, because if you can talk a lot while sounding very interesting and compelling, you can say virtually nothing about yourself but the girl will still feel the interesting and compelling emotions from your speech and transfer them to you.
If you don't care so much for the girl and are just looking for a fling, use your imagination... make something up if you want. But if you really can't think of something good to say, it means you need to work on your life more. Find a hobby, get a better job, find something you love to do. Go in a really awesome trip.
Dude, you don't even have to do anything outrageous.
I'll close with this example:
I spent the beginning part of this year volunteering at a soup kitchen at a church in one of the larger metropolitan areas of the country. That takes virtually no effort other than the time it takes google "soup kitchen" in what ever area you're in, find an email address or phone number and communicate.
When the girl asks you about yourself you say something like:
"After the new year, I like to take stock of my life and really think about the value of the things that I've done. I started to think about how blessed my life has been, especially compared to so many other people in the world right now... I spend a lot of time driving back and forth across the city as part of my job and notice how many people in need there are.... and for some reason, while I was sitting and thinking by myself on the new year, I felt a strong conviction that because I have been so blessed, I have a responsibility to use my blessing to help others.
And so I worked at this soup kitchen. And I met this person. And something great happened. ect ect ect".
If you are halfway engaged in your life, you don't have to do much to develop something good to talk about. Things will happen in your life as a natural result of the fact that you're living it.
