The little triangle are deconnected from the bottom structure!
for any reason some of your lateral curves are not joined!
make some big zoom for see it :)



You must be precise!
Disable some grid snap for keep only object snap for have good snap on extremities!
Or just grid snap and not object snap etc...

Best is redraw all the object!
Not a big deal :)

As your lateral sides are not planar you must have tensile structure
or add some lines if you want only planar facets