I am truly sorry for your loss. It certainly seems normal & healthy to want to grieve after an abortion. Many people do, even if the choice was made to protect the life & well-being of the mother. Do you have a counselor you can talk to about how you're feeling? I think that would be a good place to start.
It probably is also a good idea to revisit the medication issue. If it isn't helping enough, maybe you need to add a second med or change meds or something. Or you could have another medical condition that could be contributing to the depression (anemia, B12 deficiency, thyroid issues, hormone imbalance, etc.), so a visit to your primary care doctor might also be helpful.
Once you get any physical issues under control, you will have more energy to face the depression that's connected to the abortion. Do you attend religious services -- if so, perhaps talking to a religious leader could help? Some organizations will include loss from abortion in their regular grief counseling groups whereas others have special groups set aside for people coping with the aftermath of abortion. In any case, there are many other people out there who feel similar to you. Those groups are a safe place where you don't have to pretend anything, you can be real & say what you are feeling.
I wish I could offer you more, but your situation is so complicated. There are so many issues (history of depression, medications, relationship(s), grief, etc.) that you really do need a professional, maybe multiple professionals, to help you find your way through this. Just know that there is always a way through difficult situations. Things can improve when we make the effort to change. Everyone goes through the different stages of grief at their own pace & sometimes in their own order. And as long as you are alive there is an opportunity to seek peace (in whatever form your own values/belief system defines that to be).