any adults considering returning to school? how did you decide?

i'm 30 years old and married, but i want to go back to school and finish my degree. i've got extenuating circumstances that will prevent me from ever being able to work full time, so i'm hoping that having my degree will improve my earning potential. the problem i'm having is choosing which path to pursue in school.

i have always dreamed of becoming an interior designer, and there is a local well respected program that i could graduate from in six years, going part time. that would put me at age 36 at graduation, which is much later than i would like, since my husband and i are hoping to try to have a child and we'd like it to be in about 3 years.

the other option is to finish up my degree in psychology, which i could do in three years part time, also at a locally well respected school. this is much better timing in terms of the family planning, but also it would be my second career choice, and not necessarily the one i've always dreamed of. however, having a child is also a dream, and because of my health situation, it's better for me to try earlier rather than later.

i've never had a dilemma quite like this before. i'm completely on the middle of the fence and i can't figure out where to begin! do i commit to six more years of school (and all the student loan debt that goes with it) to pursue a lifelong dream, or do i go the quicker route in school and settle for a career that isn't necessarily my first choice, although i still feel would be satisfying?

is anyone else considering returning to school later on in life? if so, what are your motivations, goals, and reasons? i'd appreciate any input or advice anyone has.

thanks!