Indeed Allah is Qadir and the Quran always reminds us not to give up hope irrespective of how long it takes to receive the good news. Although sometimes it can be difficult for insaan to keep waiting for long without complaining. The holy prophet explained reasons as to why we think our Duas are delayed sometimes:
1. May be the dua is used to forgive our sins instead of been granted what we are asking for
2. Allah is happy to hear your voice and that eventually He grant you your wish. Many stop making dua once their wishes are granted
3. May be whatever you are asking is not good for you and that Allah replaces it with something else. Hence good things sometimes happen in our lives without us asking for it
I know it can be difficult waiting but remained positive and keep insisting, the door will be opened insha Allah