If you do a little planning and are willing to travel you should be able to see a corrida. I was there in January and there were already many events posted for the late winter/spring.
The
Las Ventas Website says they will be starting in March. Last year the first corrida was on the 13th. Keep trying, they will post it eventually. I have been there several times in March. It can be cold!
Also, try the "reventas" booths along calle Victoria, just off Sol. They often sell tickets to events in the nearby towns and have the posters outside. The bar at Restaurante Viña P on the north side of Plaza Santa Ana always has posters of the latest events in the region and you can have a racion of their excellent grilled asparagus!