If you are concerned about working with an agency or the tricky matter of paternity I suggest you find yourself a lawyer that will represent your interests.
I'm not sure what the laws are in your state, but in some states adoption lawyers can present expectant moms with families wanting to adopt, in others they can't. Either way it's a good idea to get your own so you have someone representing your interests.
Here's a link to find yourself an adoption attorney:
American Academy of Adoption Attorneys -
Any AAAA attorney should be able to meet your needs.
Options for finding a family can be: 1) Agency 2) Lawyer 3) Online Advertising 4) Private referral through friends and family.
Best of luck to you.
M