As a Muslim and an ustazah, in Islam, the soul enters the fetus at 40 days. Before that, there is a difference of opinion amongst scholars on whether or not you can abort.
I understand your situation is tight, but do believe and have hope that insyaaAllah with every child, there will be Rizq and Allah will sustain you and your family. Just as how you've made it so far with your 2 children, you can and will continue to make it.
It will be challenging of course, but you can get through this if you choose to keep the baby. You may need to reach out to get help from others as well. It won't be easy with 3 young children or look for more flexible work arrangements.
Making Du'a for you and sending lots of love 🥰 Do seek help from the FSCs and social workers!! It takes a village to raise a child and sometimes you just don't know what help and what options are available to support you and lighten your load!