Hi,
The benzodiazapenes can be very difficult long term, as you can build a tolerance to them, and rebound anxiety can be far worse. All of those types of drugs will be the same.
I strongly rec. you try to find alternatives to them.
There are a couple of drug options to discuss with your doctor.
One is Lamitrogene (Lamictal), it sounds like it might be possible that you have undiagnosed bipolar 2, which often gets worse after pregnancy, and lamictal helps with BOTH depression and mind racing, with very few side effects unlike other drugs in its class.
Also, there are SSRIs such as Paxil which are particularly helpful when depression is mixed with anxiety.
Also, for anxiety there is buspirone, which involves serotonin, different from the valium type drugs, but effective.
Finally, try to see if you can get another opinion.
And remember, it is very difficult to find the right combination of therapy and medications, but have faith - you will get there!