No nether warts in Nether Fortress (Minecraft)?

I need nether warts for a potion, and I've already found a nether fortress.

I went through the whole fortress, but couldn't find any entrance to the fortress, except for the two watchtowers.

What can I do?

Below you have the coordinates.

Thanks in advance!

Nobody forces you to go through entrances.

It can also happen that you don't find any. You'll have to look for another Nether Fortress there.