I believe that you truly love her. That isn't really the point of all this though, so I will suggest that you recognize that you are young and there will be a lot of changes over the next few years.
Her family will not really accept her "dating" anyone at that age, so I am pretty sure that whatever your dating relationship is now, that it is under their radar.
NEVER convert to any religion because of a love interest or because of your friends. JWs have a lot of expectations that are not likely going to sit well with you or your parents. Is their goal for you to grow up and do janitorial work? Or do they anticipate that you will attend university? What are YOUR expectations for your future?
Do you imagine spending at least one weekend morning (and maybe every day of your life, full time) going out in field service trying to distribute magazines or other media to your neighbors at doors?
Do you imagine taking kids to visit Santa and having warm family Christmas mornings around the tree, sipping hot chocolate and opening gifts and hearing the christmas story?
Do you imagine being part of a service organization like the Rotary or working at a food bank to help others?
Do you imagine taking your families on vacations in the summer to open stadiums without AC and sitting on hard metal bench seats for 8 hours a day and lugging in your lunch in a cooler for 3 days. In the nosebleed section, with 3 small screamingly bored children? Do you think you want people to criticize you for taking them to Disneyworld on the way home and ask why you didn't use your vacation days more productively out in field service?
Do you want to be criticized if the overtime that you have to work just to feed those 3 kids keeps you from doing "more" for the organization or accepting the privilege of being a ministerial servant?
Do you imagine your kids playing team sports, dancing in the nutcracker, singing in a choir, getting an Eagle Scout badge or basically, pursuing sports, hobbies or dreams?
Do you think it would be all kinds of fun to put your 2 month old in a little bitty baby suit and tie and take him to two meetings a week?
Do you want to be subject to shunning and discipline by a religious group because somebody took offence at the way you dress or that your child is naughty in one of those excruciatingly long meetings? How about if you get kicked out for ANY reason and your entire JW family, friends, congregants---every JW in your life rejects you-probably even your wife will reject you? Your kids won't respect or listen to you anymore, you will lose all authority over your kids and your wife will send you to the couch.
Good thing you are too young for marriage now. You are too young to have even thought about most of those issues, but I know you have a family now and you imagine, likely, that your kids will have the kind of upbringing that you did, the kind of memories, and traditions and habits. If you become a JW, there is no way that will ever happen. It doesn't guarantee that life will be miserable, but faking it all just to have won a girl will get old real quick and all the sacrifices that you made "for her" will become a contentious issue. Resentment can ensue.
Doing nice things for those you love is amazing and good and kind. Changing your religion and in doing so, being obligated to spout convictions that you don't have for the rest of your life will be soul killing. As a man, you will be emasculated. As a human, you will feel like a turd.