Will I get pregnant for sure if I preserve my eggs while I am young?

No. Fertility preservation, as the name implies, is intended to preserve fertility, not to guarantee pregnancy. It is obvious that if we preserve eggs at the age of 30, we stop the woman's biological clock there and that woman can use those eggs at the age of 40 and will have a higher percentage of becoming pregnant. But no one can guarantee a pregnancy because concomitant pathologies can appear later on that can make pregnancy difficult even though we have 30-year-old eggs.