Is a bad idea (physically) to have another child? septate uterus and c section scar?

I have had 3 c-sections so far and I will have my 4th and final one in late July. I found out during my last c-section that I actually had a window defect (a hole in my uterus!!). It was there from my 2nd c-section. I had a hole in my uterus for almost 2 years and never knew it!! However, I carried and successfully delivered a healthy baby. I am currently 11 weeks and 6 days pregnant with number 4 and I do pose a high chance of still having the window defect due to my uterus thinning and weakening from previous pregnancies. My OB/Gyn explained to me that the part with the whole is actually my uterus fading away!! He did reure me that no one has died or had any serious effects from this in over 15 years!! They are confident that this pregnancy will be smooth and that I will deliver another healthy baby at full term!! However, as a result of this they are going to tie my tubes to prevent any future pregnancies! But that's okay with me!!