cindy,
I agree with the others, and concur with the suggestions they've offered. After all the planning and anticipation, it would be unfortunate to cancel the trip at this late date. While it would have been nice to have someone to share the trip with, there are also advantages to travelling solo.
In addition to being vigilant and "situationally aware", be sure to wear a Money Belt under your clothing for storage of important items like credit cards, Passport and larger amounts of cash. Do NOT access it within view of others. There will be pickpockets at work, especially in Paris.
If you'll be staying in Hostels, I'm sure you'll be able to enjoy some of the Pubs in the Temple Bar area in the evenings, as you can walk down there with one or more people from the Hostel.
Hope you have a wonderful trip!