Why is the event so short?

Events are available within a certain time frame. Crafting events also require the player to have reached level 12. The time frame for the “Charming Cottage” event is from May 20 to June 2, which is just over 13 days. If a player starts too late, they will not have the full 13 days available for this event. 
You said that you only started playing a few days ago. So you had to reach player level 12 before you could start this event. This is unfortunate, but you may have the opportunity to catch up later when it is repeated in a future update.
Not too long ahaid there will be a new update with other events you can participate in :)