Too young?

Hello everyone! Thanks for taking time to read my posts, any advice will help! My dh and I have been struggling with fertility for almost three years now. We have found out it is nearly impossible for us to have a child biologically. So, we moved onto adoption. This wasn't a huge step since my little sister (who is AA, has quadreplegic cerebal palsy, is the light of my life, and just turned 14!!!) was adopted at the age of 6 months old, I also have many cousins who are adopted. My dh and I got a very early start on life, working full time since we were both 16, and starting work when we were 14. We knew what we wanted from a very early point in our lives. My husband has finished school, and we are both in great careers! The only issue is we are 21. We will be 22 in march and may, but are still very young. I was wondering if this was a big issue with birthmothers? We own a gorgeous 3 bd, 2 bth home (sorry, don't mean to brag :-) ) and have stable careers, but i have gotten a lot of the "your too young to adopt" from many agencies. It is disheartening because it is not unheard of for a 21-22 year old to have a child, so why is it such a big factor for adoption? I do realize how special and unique adoption is, and it requires so much love from all people involved. I just was wondering if we should give up our quest for a while? We really want a child and don't want to wait until we are 25, we can proceed to IVF for last means, but we really would rather not do this because of religious beliefs, we just feel backed into a corner. Anyway, i thought some insight would help, i'm so sorry if this is inapproprate!! Thanks guys!!! natalie