Can I still be disfellowshipped after all these years?
It's all up to the local elders and the CO. The general "rule of thumb" was if the people in the community considered you a JW, then the elders would feel compelled to act. However, it sounds like you've moved across the country and have never gone to the new Kingdom Hall. Unless there is an overzealous CO or the local elders feel like having a df'ing party, I'd be surprised if they did anything. But remember, anything is possible with these guys.
The most important thing for you to remember is that you need to do what's best for you, your husband and your future kids. It would be nice if your mother understood and respected your freedom to choice but don't let the fear of upsetting her stop you from doing the right thing.
Some people fade, some people don't. I chose not to. There are pros and cons both ways. I liked the fact that I didn't have to "sneak" around or pretend to believe something is true when I know it's not only wrong but harmful. I liked sitting in front of these elders I served with and respectfully explaining why it's not the truth and that they do not have any power over me. For me, it was pure freedom. I also did it for my kids. I didn't want them to have the "outcast" JW life I had as a kid. You know what I'm talking about. Having to sit in the school library while the other kids celibrated a b-day or some holiday. BTW, you'll be overjoyed at seeing the things they will experience in their "normal" non-JW life. Things you and I missed out on.
I feel weird about starting to celebrate Christmas
I did at first but you'll find it has less to do with religion then it has to do with spending time with your family. My kids and I have been attending the family Christmas party and it's great to see aunt and uncles and cousins at least once a year.