All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Firstly, we ask Allaah to bless you with righteous offspring, and our advice to you is that you earnestly implore Allaah and never give up hope. Verily, Allaah is able to do all things, and for Him nothing is impossible. One of the most important means of attaining the blessing of offspring is Istighfaar (asking Allaah for forgiveness); Allaah, The Exalted, says (what means): {And he said, 'Ask forgiveness of your Lord. Indeed, He is ever a Perpetual Forgiver. He will send (rain from) the sky upon you in (continuing) showers and give you increase in wealth and children and provide for you gardens and provide for you rivers.} [Quran 71:10-12]
So you and your wife should make as much Istighfaar as you can.
Adoption is prohibited in Islam, as we have previously explained in fataawa 82371 and 84422. You did well by seeking to abide by the teachings of Islam in this regard. It is a praiseworthy deed to take in a child and look after him or her; however, if the only way to achieve this is to adopt the child, then it is impermissible to do it, especially given that there is no necessity entitling you to opt for this solution. We emphasize the need to seek medical treatment to have a child, even if through IVF, provided that the due conditions set by the Sharee'ah in this regard are met. We have previously underlined this in fataawa 82554 and 84882.
It should be noted that such laws that stipulate adoption to be able to accommodate an orphan child are among the most evident manifestations of the perils of living in non-Muslim countries. Living in Muslim countries spares the Muslim such inconvenience. The Muslim can easily support a child in Muslim countries without the need for adoption. Your wife can find comfort in the affectionate relationship with her relatives and neighbors and their children, instead; please, refer to fatwa 179175.
Lastly, we advise you to consider taking a second wife; hopefully, you could be blessed with children from her who would be a source of content for you, your second wife, and your first wife as well.
Allaah knows best.