I am not noticing a huge increase when it should be

for example, I had like 1,5k DPS multiplyier to use and from 1,39e111 dps y just raised to 3,46e111

That doesnt sound to me like 1 x1,5k plus DPS increase...

Since the skill is additive, you'll see decreasing returns each time you use it. The formula works as...

(DPS) x (1 + Base Storm Rider buff x number of times used)

So let's use small numbers to make this easy to read. Assuming your base DPS is 100 and you Storm Rider buffs 50% per use...

If you use it once: (100) x (1 + 0.5 x 1) ---> 100 x (1.5) = 150

If you use it twice: (100) x (1 + 0.5 x 2) ---> 100 x (2) = 200

If you use it thrice: (100) x (1 + 0.5 x 3) ---> 100 x (2.5) = 250

Notice how 150, 200, 250 is not adding 50% of the previous number each time (150 + 50% would be 225). After so many uses, the visible change in your DPS becomes less and less impressive.