Spend part of the day looking for one or two therapists. You want someone who can do couples counseling and someone who can do premarital counseling. The latter can be a minister, although, in your situation, I'd try and find someone who has psychological training, whether this is the same individual or two. Find someone you can talk to comfortably. This may or may not be the first person on the list. Also, do not be hesitant to switch counselors if one is not helping. (If money is tight, you can often get references for people who work for reduced rates so inquire with local family services in your area.
Get yourselves fixed, first, before entering into a marriage. If she is not interested and cannot see the value and wisdom of receiving some sage advice, then you have a decision to make. In and of itself this tells you she is still immature.
Regardless of what the arguments seem to be about, it is important to talk about issues and not topics. Learn how to argue--meaning how to negotiate and arbitrate. This means learning how to be a good listener and hearing what the other person has to say and working to give him/her the most of what they want without giving up the core of what you want. People often fight about topics that have nothing to do with the real problem.
> We can't get along, every 2weeks we have an argument and I personally think the argument is based on her being mad at me for not wanting to get married.
This may or may not be the case. Another important tool the two of you need to develop is the art of communicating. I mentioned above what part of this entails. Learn to talk, learn to listen, learn to get the real points across.
Here is an article listed in the Index that I hope will be helpful to the two of you. Encourage her to read it also. Knowledge is empowering.
I think we are ready to live together!!
We frequently hear about people living together who later find that one, the other, or both are not happy living together. Similarly, we frequently read a post in which a couple is contemplating moving in together and looking for a suitable residence. Here is an initial Check List.
Lastly, wake up every morning and ask yourself "what can I do today to make her life and the life of my son better", then set about doing it.