NTA.

Her trauma is not your burden to carry. It's sad that she has had 6 miscarriages, but she has to accept the fact that life moves on around her and she will witness pregnant women all the time regardless of her situation. You deserve to announce when and how you want to. I'll probably get DV for this but 6 miscarriages is not "6 dead children." Stillbirths are, but not miscarriages. She said that as an emotional manipulation tactic to drive home her point and hurt you. Her angered is misplaced.

If she is THIS affected by your pregnancy announcement, then SHE needs therapy. Bad. She would have been upset still even if you told her ahead of time. It's not the announcement she is triggered by, it's your pregnancy.

Congratulations. You deserve to be happy.

What do your parents and husband think?