What if I don't want to have my ass kicked?

I am in the middle of a master's program that is for me a liberal arts major is very challenging. I am relearning much of the math I've forgotten over the years and doing ok, but not cruising along in Chemistry. I'm attempting to add an endorsement to my run-of-the-mill Elementary Ed Degree, and become a high school (with the possibility of college) chemistry teacher.

I enjoy science and was and am always interested in how things work, what the universe is made of, etc. But at this point in my life (mother, wife, teacher, landlord) and I able to tackle this? If I elect to get a MA in ELL or Instructional Design or something similar, will I always look back on the program as a failure, or something that could have been? My father always encouraged me that I could do whatever I wanted, and I believe him to be true, but is this what I want- in perspective to everything else I want?

Here's what I want: I want to enjoy my life. I find that I sometimes get frustrated with my son because I feel the pressure of working and he wants me to play (which is something else I feel pressure to do). I want to be a good wife. I want to have the energy to do many other things that interest me. I think teaching is what I want to do with my life, it seems to fit my personality, though I'm not completely sure that I will always want to teach the same level of student and may be interested in getting into adult ed. I think I am at least kind of interested in getting a PhD at some point. I may consider principaling (maybe). I want to have time to read and write and take yoga and have another baby and spend time with my husband and children. I want to make the home life for them that I missed out on. I may be interested in teaching in another country when my kids are bigger or grown.

I have always been a bit of a grasshopper, and wanted to work less than the fun I have. I skated through much of my education, and honestly, I'd like to continue to skate. Just something I'm thinking about.