Can't really tell from what's provided, but if you used that lvextend command, did you not use the -r option? That would have increased the file system size to use free space in the LV. Without that, you need to manually resize the file system.
If you want better help, please post the command and output from these:
Code:
sudo pvs
sudo vgs
sudo lvs
lsblk -e 7 -o name,type,fstype,size,FSAVAIL,FSUSE%,label,mountpoint
df -hT -x squashfs -x tmpfs -x devtmpfs
Wrap those command and output in forum code tags so the columns line up correctly. Without that, it is too hard to help.