I started dating my boyfriend before my diagnosis and he's been through it all and we're fairly happy.

Normally had I not been lucky off the bat, I think if I was to date there probably would have been a lot of rejection. I think it's normal though. I think your mom is probably trying to protect you because she's afraid a rejection and loss could trigger you. (The thought of that triggers me...) I think you should date if you feel ready. Since you're just testing the waters don't get too attached to anyone in the beginning and use it as a learning experience.