120 ml in 25 seconds is about twice as much as usually recommended. Try for 50-60 ml in 25 seconds and see how you go.
Otherwise, Im not sure what the problem is.
Fresh beans, freshly ground, decent machine, lots of crema...
When I do the same I will often get 80-90% of the initial pour to be crema. It then subsides quickly to a layer on top, and then over the next minute or so (if it lasts that long) to a rim around the cup.
Maybe you need to drink it faster?
If the taste is right, its right.
ps--you didnt mention what grinder you are using.
pps--nicely warmed cups?