Unfortunately this is part and parcel of having a j-pouch - there is significantly reduced chance of conceiving. Actually, this is the case with many pelvic surgeries due to scarring, but my surgeon did say that the chance of getting pregnant may be as much as 40% reduced with the j-pouch. He suggested consulting a fertility clinic if I did not get pregnant in the first 3 months of trying.
The thing is, you are basically between a rock and a hard place. In my case, the colectomy literally saved my life. I almost died from UC. I had no time to consider consequences and I went forward with what I knew at the time. A lot of things I didn't learn until later, but I've accepted them. And fortunately, I am not currently in a relationship or trying to get pregnant so it is a non-issue for me.
Now, this is certainly not to say that you cannot or will not get pregnant, but you do have to know the statistics. Many women here have had successful pregnancies with the j-pouch. In fact, there are a multitude of threads on this issue in the Women's Health and Pregnancy forum on this site, and you will find plenty of useful information there.
Best of luck in your journey!