Yes, you should be going anyways. If you are having a normal healthly pregnancy( it's not an illness or a disease you know) AND your doctor oks it, then GO! It will be your last relaxing holiday for some time!!!
I've gone to Disneyland pregnant AND gone on all the rides( yes the ones with warning signs too!) all three of my kids were fine !
You are pregnant, not crippled, if you feel ok, and Doctors says ok, then what is the problem.
Yes there is a remote chance that you could go into labour, but that is a small chance, plus if you are less than thirty weeks, even if you are at a hospital there is no guarantee that your birth will be successful. They do have a way to get you off the ship quickly, ( helicopter) and there are hospitals in Alaska and an excellant childrens hospital in Vancouver ( plus serveral others)
On the other hand if this is your first child you are probaly very nervous( excited) and if you really think you will be too uptight to enjoy the cruise ,then don't go.
I would though!
The one other( very important) thing that you must check is will your medical insurance cover you in the event of a problem. That is vital !!