I'm so sorry OP 
I'm involuntarily childless due to infertility and it's shit
I can also recommend Gateway women, and a number of FB groups for women who are childless not by choice
Books that are super helpful include:
Living the Life Unexpected: 12 Weeks to Your Plan B for a Meaningful and Fulfilling Future Without Children - Jody Day
Motherhood Missed: Stories from Women Who Are Childless by Circumstance - Lois Tonkin
Finding Joy Beyond Childlessness: Inspiring Stories To Guide You To A Fulfilling Life - Lesley Pyne
Beyond Childlessness: For Every Woman Who Ever Wanted to Have a Child - and Didn't - Rachel Black & Louise Scull
Life Without Baby: Surviving and Thriving When Motherhood Doesn't Happen - Lisa Manterfield
Silent Sorority - Pamela Mahoney Tsigdinos
Ever Upward: Overcoming the Lifelong Losses of Infertility to Own a Childfree Life - Justine Brooks Froelker
Otherhood: Modern Women Finding A New Kind of Happiness – Melanie Notkin
Dreaming of a life unlived - Yvonne John
Dear You: A Letter to My Unborn Children - Tessa Broad
You might also find these books offer a different perspective on the social expectations of motherhood and females identity:
The Baby Matrix: Why Freeing Our Minds From Outmoded Thinking About Parenthood & Reproduction Will Create a Better World - Laura Carroll
Baby Hunger: The New Battle for Motherhood - Sylvia Ann Hewlett
Reconceiving Women: Separating Motherhood from Female Identity - Mardy S. Ireland