Is it too late to become an engineer?

Hola, Rocio, it is NEVER too late to become an engineer. 

I think the first question I'd ask is "what did you like about law in the first place?" something had to appeal to you -  make sure that before you make a career change that you do all your "homework" to mitigate the risk of eventually feeling that you made a mistake if you switched.

Selecting a major and potentially deciding what you will do "for the rest of your life" is difficult to do as a teenager (and even adults have the same problem!). Even when you know that you want to be an engineer, you have the decision about what engineering you would like to pursue.

I don't think TIME is a constraint at your age. The first year of college helps you decide if what you selected is what you'd like to pursue or if switching would be a better decision in the long-run. If you decide to switch you may feel that you lost one year but instead you learned what you don't like to do when you have 40+ years of a professional career.

I am Colombian, and my switch was from being an engineering student in Colombia to transferring to the US to finish my degree in Houston.  I had to lean English and in addition, by homologizing my credits from one school to another I "Lost" a total of 2 years but I was happy and in peace with my decision because I wanted to do a PhD and that degree was not available in Colombia. It was the best decision for me and something that I knew I had to sacrifice in order to achieve my long term goal. 

I believe your mom wants the best for you, and wants to protect you - she is probably talking from her own experience about what she knows about engineering and I know that you appreciate her opinion and her honesty.  I suggest that you talk to her, ask more questions, share with her this website, and the opportunity to make a difference being a successful engineer and try to get her blessing in pursuing what you feel will make you happier. 

Engineering is so broad, flexible, and a career that you can practice wherever you go - I think law is more restrictive as you learn the laws of one country and if you want to move to another country later, you will have to start all over again.

Both careers are great, especially if you are the best in what you become, however, I personally love engineering because it has opened the world for me.  I know it will also open a world of opportunities for you.  Please feel free to contact me at any time.