First of all don't be petrified, we are all human ,we make mistakes ,sometimes are good dreads become bad and vice versa ,unless your daughter was raised stupid and clueless ,she may not know you yet, however she should appreciate your sacrifices to give her life and to give her to someone more able to give her what she needed . I was adopted and know my birth mother loved me ,after her murder ,I was taken away from my father , I accidently found another mother to love me , your daughter may or may not realize how lucky she is ,finding one mother to love is hard ,to have two in one life is an extraordinary gift.
You obviously facilitated and were integral to both parts of her life , she almost had the easy part ,she was going to grow up either way ,hopefully her growing up was filled with opportunities and adventures you may not been able to provide her for the last 30 years,she's not a stranger she's is family ,you are family and it's not a new concept she knows she was adopted,how willing she is to find out about the why's is the only mystery .

In some ways you have to let her lead , in discovering who you as the mother who wanted the very best for her ,don't try and fill her with with knowledge (That's our instinct as people) let her ask the questions ,answer them truthfully and honestly , both of you are traumatized in your own right about giving her up ,you both need to heal from it ,and then once you do the dialog becomes alot easier and spontaneous, when no one is walking on egg shells .

I have lots of friends who were adopted and lots of them searched long and hard to uncover there own roots,with closed adoptions thru agencies and attorneys that don't exist anymore and many dead end leads they persevered, and though rocky in the early days , most of them have fantastic relationships with all there families ( I have one friend who lost to death her adoptive family ,but her biologic mom's family is very close to her and keep her "anchored")

Your anxiety is real ,and it may not be an overnight instant connection, but is anything we are given truly have value? As opposed to things we value because we worked for it,and made our own .

Re engaging in your daughters life demonstrates the same love and care you displayed 30 years ago ,
And this is just my opinion but until we are 30 we don't have what it takes to make good decisions,book knowledge without experience makes us young and stupid ,take that same knowledge and temper it with experience of the world ,that's a winning combination .

So this time it very well could be the time that works best for both of you ,in developing a relationship ,when my adoptive mom died we where not parent/child traditional dynamic we where equal adults having a good time , yes I could always ask her stupid questions because she had more time on earth (like any parent child ) but 99% of the time ,we were best friends .