Hi jsim92480, I am so glad that you have reached out here. I hope we can give you some advice, suggestions and lots of support. So please know that whatever you write here is safe.
Depression can actually be genetic so, if your mom has had it she could of genetically passed it on to you. It sounds as if you didnt like having to take care of your mom in that way so I would very much doubt that your depression is learned behavior. Depression is a serious illness that indicates a low serotonin level in the brain.
I can totally understand not having the money for doctors, co-payments and such. But if your feeling this way then please do seek help. Perhaps if you call your primary care physician and explain to his nurse what is going on they may prescribe an antidepressant over the phone for you. There are many that are not that expensive any longer...but you can always see if your doctor can help with samples. Not only that, but most all drug companies who make antidepressants have started programs for people who cannot afford them, you can get them for very low cost or even free depending on your household income.
Depression is treatable...I know first hand that when your going through it, it doesnt seem like it is but you have to have faith.