You have wanted to learn how to play the ukulele because you know that this is the easiest string instrument to play. It does not mean that just because you can play a lot of songs with it, you will be able to play some of the hardest ukulele songs immediately. Some of these songs are hard because of the complicated strumming patterns.
For example, Viva La Vida by Coldplay has average chords but the strumming pattern is exquisite. Breaker, a strong by Deer Hunter is complicated because of its chords. You may have to teach your fingers to play the chords immediately and easily. Another song is Everybody Wants to Rule the World by Tears for Fears. There are complex chords that should be used to play this song well. The fact that you need some of the 6th and 7th major chords might make you a bit frustrated.