I can understand your anguish, however I would imagine each woman will consider her own situation before deciding on a termination or otherwise of a pregnancy.
You know there was a sahabi, who during the jahaliyah period killed his daughter. Because the Arabs in those days used to dislike female children, they would bury them alive, this sahabi did exactly that to his daughter, many years later after he had embraced Islam he still wept at his actions and begged forgiveness of Allah swt.
There is a passage in the Quran which goes something like, Kill not your children because of poverty – We provide sustenance for you and for them.
As for duas I think this might help;
Transliteration: LA HOVLA WA LA QOOVATA ILLA BILLAHIL ALIYIL-AZIM
There is no power and strength except with Allah, The Grand, The Great.
Also if I were you, go and consult an Imam who follows your school of thought, about the validity of the length of time passed before you terminated your pregnancy and stick to that ruling, doesn't matter what other arguments there might be out there, you cant follow all rulings of all schools of thoughts, just stick to the one.
There's nothing you can do about the past, repenting and meaning it, and resolving not to repeat your mistake is as much as you can do, and Allah is the most merciful.