I think people say insensitive things unintentionally when they don't know what else to say. Tell people that are trying to support you that it's okay to not say anything and that sometimes you just need a hug or something to divert your energy and senses somewhere else. Because my friend told me that hey you guys were arguing recently maybe wasn't the right time for a baby to come and I wanted to punch her in the face. I don't think your mom did it intentionally at least it's not as if you have a good relationship prior to your pregnancy. I know you feel like crap because I definitely did feel guilty over an argument and it had nothing to do with the miscarriage. I know it's really hard and you feel like you failed but God knows best if your religious. And nothing can happen before its time when your body is ready it will be again for you and I'm wishing you the best in healing emotionally and physically and baby dust to you when you try again.
There is nothing u did wrong! Ur mother should be supportive not try to bring u down. Just keep ur head up!