Will I definitely become infertile?

There is no evidence to suggest that puberty blockers negatively impact fertility.

Cross-sex hormone therapy may negatively impact fertility, although this is not guaranteed. If you wish to have biological children you should consider fertility preservation treatments before starting cross-sex hormone therapy.

Some surgical procedures involving the reproductive organs, like hysterectomy (removal of the uterus) or orchiectomy (removal of the testes) will result in irreversible infertility.