I actually think you are coming to some very important realizations to take the next steps. The key is to start taking those steps.
Understanding what triggers depression is a huge accomplishment. You stated your depression came to a head many years ago when you were unable to support yourself and pay for basic needs. I can imagine your current situation is a huge trigger as you not only have to support yourself but two young children.
Instead of wondering what issue to tackle first (depression or possible ADHD) why not make an appt. with a psych that might be able to advise you on both issues? I know it will be hard to actually do it but I really do think you will be amazed once you really get a handle on what is going on in your mind/body. I am not saying life will all of a sudden get easier but things will seem more clear.
I am also self employed and I can relate to all the trials and tribulations self employment brings. There are thousands of online groups for self employed women. It doesn't really matter what your business is, the general concept is still the same. I would imagine your area has a "real life" small business group for women. Most any issue you run across as a self employed person (time management, childcare, marketing, accounting and so on) somebody else has experienced and can offer you support, resources, encouragement, networking and wisdom.
If working outside the home is not a feasible solution for you right now then you must find a way to make your self employment work. I actually think you are in an ideal position. Right now you have the opportunity right in front of you to get the ball rolling with your self employment so you can be with your children. The longer you wait the more that window will close and eventually you may be forced to take a job outside the home making a low wage just to survive. If you have the opportunity right in front of you to resurrect your own business to (A) earn an income and (B) be home with your children don't let it pass you by. If you have obstacles (depression, ADHD) that are preventing you from tackling your business, no matter how hard it is, you must get those in check first.
I am not over simplifying this at all. I almost lost my business due to depression, anxiety and a panic disorder in addition to the chronic illness I deal with each day. I am not saying it is easy but it can be done. You will need support from friends and family, you will need support on the medical side and you will need support from other women who have walked or are walking in your shoes. The good thing is ALL that support is readily available if you can just find it within yourself to get started.
Think of what you can do to make one improvement this weekend. If your office is a mess and chaotic get it cleaned out. Maybe new carpet and a new paint job is not feasible this weekend but I bet organizing, purging and removing some clutter is an attainable goal.
Check out apartment therapy (website). It is a fantastic place to get inspiration (on a budget) for small living spaces.
