What you are doing is exactly what I did. I always wanted to be a nurse (from age 6), I attempted to right out of high school and failed out of my general classes because I was having WAYYY too much fun! Then I met my husband, found out I was pregnant. I still wanted to be a nurse, but with a baby on the way I didnt want to be in school for 4 years, and I wanted weekends and holidays off with a nice 9-5 position in a clinic, so I became an MA. I worked as a Medical Assistant for about 5 years before I decided to go back to nursing school. At that time I had a 6 year old and a 2 year old, it was definitely hard, but I wouldn't change a thing. It was the best decision I ever made, and now I work as an ICU nurse.
If this has always been a dream of yours, and you love being a medical assistant and helping people, you will love being a nurse. Always follow your dreams, and if you have a means to go back to school right now, just do it... I have a feeling you won't regret it. Also, being an MA will help with schooling a little bit because you have knowledge of certain meds, procedures, lab results and terminology. When I was an MA, I always thought, man if I can do this then I can be a nurse... then I started my junior and senior year of nursing school and realized how much more nurses know, learn, and are responsible for (huge eye opener), but once again, very worth it! If you are wanting to further your education, and increase your knowledge and skills, then you are ready! I will never look back!