I'm adopted too. Before you go to all this trouble, there is an agency in Austin, Texas that handles requests for adoptee to see their original birth certificates. It's not expensive. I did mine over 10 years ago & I can't remember where I put the file. Look on-line. Since you are over 18, the law allows you to access this information. Also, if any of your siblings and/or bio. parents have signed up to contact you with this adoption registry, this agency can put you in contact with each other.
I'm sorry that I'm so vague but it's been over 10 years since I did this search. I'm a lot older than you so my information was sketchy. Yours might be more productive.
If you want to contact me directly, give me a call at 713-847-6000.
I do want to warn you that mine was not a "happy" reunion. You need to be prepared. Often there are reasons why you were put up for adoption that are not pleasant. Are you sure that you want to know? It can be quite hurtful & sometimes, not even truthful.
Most steps have a REunion Registry. First check out to see if Texas has one and how to access this. A reunion registry is operated by the state and they will assist you in getting information about your birth family and possibly opening your adoption file. It is free and you do not have to pay anything to do this.
Counseling before you embark on this mile stone is highly advised. Good Luck on your journey