Aim: The aim was to investigate same-sex mothers’ self-assessed experiences of forming a family, and the association between heteronormative information, parental support and parenting stress. Design: A quantitative, cross-sectional study. Methods: In a web survey conducted in Sweden in 2019, same-sex mothers (N = 146) with a child aged 1–3 years answered questions about their experiences of forming a family through assisted reproduction and questions about parenting stress. Descriptive statistics describes the process of forming a family. Pearson's correlation analyses and independent sample t tests were used to test hypotheses about heteronormative information, parental support and parenting stress. Results: Same-sex mothers experienced going through assisted reproduction treatment as stressful, and parental groups as not being supportive. Heteronormative information correlated with both lower perceived parental support and higher perceived parenting stress. Non-birth mothers experienced less acknowledgement and support than birthmothers.