I was in your position 12 years ago, except my dc were older.
I went through all the what ifs - youngest was about to leave primary and an end to the school run was on the horizon; all sorts of other insurmountable problems.
DH was adamant he didn't want another child. Went to DM for advice and she was against as well. Some of our dc have SEN and I knew if I asked for help, both DH and DM would not want to help.
Even sitting in the clinic I knew I didn't want to go through with the termination, but really needed someone to give me "permission" to have the baby. Of course by the time the due date rolled around, all the insurmountable problems had melted away.
3 years of carrying the guilt around, and DH admitting he felt we'd made a mistake, we decided to try again. I had 2 miscarriages, which DH felt was punishment, then 3rd time we were lucky. But with a massive gap, which is far from ideal.
What I would say to you is that you've only mentioned the effect on your other dc/house/car. Not you. You need to forget about all the problems; they will disappear. You need to think carefully about what you want.
If having thought carefully you really can't bear the thought of doing it all again then it is perfectly OK to go for termination. But if you actually really want this baby then don't be swayed by difficulties, because you will manage. You will have to live with your choice so you need to be sure it is right for you.