I-130

If I was petitioned by a family member with I-130, if I turn 21 and still haven't been totally approved, will I lose this chance to get my immigration papers fixed? We already received preliminary approval, like, we got that letter from USCIS that they are reviewing it. But if I turn 21 and still haven't been approved what do I do?

When was the petition filed ? You should also ask USCIS if you're covered under CSPA.

As long as the petition was filed before you turned 21, you're OK. Your "CSPA age" will be calculated by subtracting the amount of time between original filing and petition approval, which is delayed until after a visa becomes available. Normally petitions are approved first and the you wait for a visa, but with CSPA they wait for a visa spot to be available before they process the petition.

Aside from that, you must be grandfathered in for the 245i provision for you to be approved while residing unlawfully in the US. You qualify as long as you were mentioned in an old petition filed before the cutoff date in April 2001 (among other things) and you pay a $1000 fine.

Even if someone files after 21 years of age, the wait is just much longer because you would be in the over-21 category. If being petitioned as a single child, however, then getting married would nullify that petition, so you can't use it as a backup if marriage doesn't work out. It could also be nullified if the sponsoring relative dies.