I definitely have experienced what you are describing. I "lost" myself in baby #1, then baby #2 came along 14 months later. He is just past 2YO now, and I am trying to rediscover myself after more than 3 years of being in mommy mode 24/7/365.
I really didn't know where to start. Then I decided to read! I was reading all along, of course, but only parenting type books with an occasional work of fiction thrown into the mix. Now I have been reading non-fiction to stimulate my brain. I have hobbies that I used to do, but I'm not sure I want to resume them. It's a slow process.
Actually, I have found myself going back much farther than just the couple of years pre-children. I think I was also "lost" in the corporate world so now I look to my college days as a guide to rediscovering myself, since that is when I was first "finding" myself anyway. I did awesome thinkgs back then, like helping to start a women's center on campus, participating in a consciousness-raising group, being active in animal rights, writing poetry, composing music, etc. I was so fully alive, and now I am looking to incorporate that young woman's spirit with the part of me that is now mother. It is a fantastic fit, actually. Becoming a mother has brought back to life the part of me that died while I was immersed in corporate America.