Stop thinking with the little head. Let me do some crystal ball gazing for you an dlook into yoru future:
You get baptized to improve your relationshiop with your gf's family. Then you marry her and have kids and your kids are brought up as Witnesses and subjected to the indoctrination they use to induce sub-conscious phobias that they can manipulate as your child grows older to keep them in and stop them developing critical thinking skills. Years later you wake up to the full horror and see this manipulative cult for what it is and want out. You get disfellowshipped and your wife shuns you and encourages yoru kids to do the same - she gets help from the organisation to win custody of your kids on the basis you are spiritaully weak and a bad influence. Later your kids also wake up and realise the psychological damage this cult has done to them and resent you for not doing more to get them out.
This scenario is by no means fanciful. I am not suggesting you need to break up with your gf but if you are going to stay with her do it on your own terms and be clear you will not be converting and you will actively oppose your kids being brought up as Witnesses. This will test how liberal a Witness she really is. If she walks away you know you have dodged a bullet because she is telling you the organsiation is more important to her than you. If she stays then you have good prospects of getting her out (though recognise that it wil be a long hard bitter struggle to break the spell of indoctrination but it will be her seeing your genuine love for her that will win out in the end).
I think it is ironic that so many people on this site will tell you to end the relatinship point blank because they don't give Witnesses any credit for being able to get out when they themselves have done so. My wife was brought up in the cult and baptized and very much under the yolk but over time I have gotten her to the point where she has not gone to a meeting for 18 months and didn't even go tot the memorial this year. .