Hello please help have i commited an offence?

so i met this girl online and she got me to send her some pics off my Kock and i kno your lookin at this and thinking stuppid kid but i spoke to her for a long times all day everyday and i sent it her she told me she was 17 and then she told me she was 16 and i didn't kno how old she was and i was kinda going out with her online (BIG MISTAKE) and she sent me some things which i regret all off this and i kno longer speak to her after 1year she left me for some other boy in reall life can i get into trouble for this she made old enough have i commited an offence here? could i go to jail for it i was only 16/17 my self i dont kno how old she was about 16 i think thats what i thought she was can i go to prison for this she asked me to send them her i wish i never now (BIG MISTAKE) and i latter found out that when she was 15 she had sex with a 20 year old (NOT ME) but can i get into trouble for sendin them pics did i commite an offence