The only thing I can suggest myself, and this probably isn't the case, but I'll try...
For me, I go a couple days without sex/masturbation, and I can spray the walls with DNA. I go at it too much, and its a trickle.
I've also found that (for me), morning orgasms are weaker than late-day. Haven't figured out that one either
I'm not trying to suggest that you can't take the frequency anymore - hell, I was like this when I was 18, nevermind almost 30 now myself. If you take a break though you might find things strengthen up again.
Not sure if that helps, but my 2 cents
Sammy