Good for you for wanting to better yourself! No sense looking back at things in the past-- get into nursing if that's what you love.
I'm doing that right now. I'm attending Maria College in Albany NY and will get an associates RN. My classes are all at night, but I do have to schedule a clinical day per week. I'm doing a 3-11 on Mondays-- I'm self employed so I at least have schedule flexibility.
Call around to local nursing schools and see if they have any night programs, or know of any. Community colleges sometimes have them.
You might be able to do medical billing right from your home. I think billers get paid according to how many bills they submit (but I may be wrong) so you could work around a nursing school schedule. Phlebotomy as a day job may pay well enough to support yourself and son. If he's old enough to work, he can supplement your income too. You might also qualify for some sort of public assistance. Some nursing schools have assistance available for qualified lower income students. Where there's a will, there's a way!!