I used to be able to cum but now I can't!

Hi Worried user
Was your bit of ejaculation white coloured before?
The clear sticky stuff does it come out part way through when your masturbating or does it come out at the end when you orgasm?
If you are masturbating a lot you could try giving at a break for a few days and see if that makes any difference.
Depending on how far you are into puberty you could still have the odd dry orgasm or occasionally just get pre-cum giving it a break for bit is worth a try.