We have 3 children, our youngest daughter is adopted.
Our dd is my dh's cousin's birthdaughter, so there is some family connection there and it is an "open" adoption. Therefore, we had a lot of family "opinions" good, bad, and otherwise about how we cared for her. Thankfully, the family lives about 900 miles away, so we don't have to hear those opinions face to face too often.
DD is 3 months younger than our youngest ds, so that could have added to some of the stress surrounding our adoption. Having already birthed three children, I thought the minute I held her I would fall madly in love with her and feel all sorts of maternal bonding. Not so. DD had been exposed to all sorts of drugs in utero and was a screamer. She did not want to be held, she cried all the time, to the point that we had to let her scream in her crib with towels under the door frame so she would't wake the others. Hard to bond with a baby who doesn't want to be held. I tried to nurse her, but she was a very lazy nurser and made it difficult to nurse both her and her brother.
She was born out of state, so we had to go through the whole adoption process just like anyone else. We had to have a home study done, where they interview you, your husband, your children, your neighbors and friends. Also, we had to be fingerprinted and everyone in the house had to have a dr's physical exam. It took about 6 weeks before the paperwork was finalized and we could bring her home. During that time, she was with her birth mother for 2 weeks and then, when the drug screen came back positive, she was put into the care of my in-laws (they live in the same state and could take temp. custody without any issue.)
She is now 3 1/2 and she is a very sweet girl. She does have some difficulty because of the drug exposure: can't sit still at all, some resp problems (RAD), but for the most part she is doing great.
It can be a long, difficult process, but if you and your husband truly feel that there is another baby out there for you, then I would go for it. I think I was expecting it to be all rosy and happy and tra-la-la-la-la we have another beautiful baby! It wasn't. It has required a lot of prayer and grace to get us through these last three years.
If you have any questions, you can PM me and I will be glad to help you!
Best wishes!