rosebud - you are right , there are many children in care waiting for a family. however, most of these children are school aged, or have special needs or are in sibling groups and many are black or of mixed heritage and awaiting a family who reflect this
If you feel that you could parent a child like this then adoption may well be for you, at some time in the future. however, as KC says, you will need to have an age gap of several years between your youngest child and the child you adopt. This is so you can give the new child enough attention.
yes it woudl be possible for you to be approved to adopt a girl, or even a sibling group of several girls!
however, there is a long LONG list of couples already approved and waiting to adopt young white healthy toddlers and babies ( boys and girls). you will understand that adoption agencies will probably give priority to families who cannot have bio kids, so you are unlikely to find an agency willing to even accept an application from you for a NT baby or toddler.basically its pointless for them to spend time preparing you and approving you when there is no chance of you having a child placed with you.
have you thought about doing soem voluntary work with children? This would be good experience if you did decide to adopt later
Good luck with your pregnancy