Advice please?

Aoife
So I've just gone 18 a few weeks ago and my mum suggested going on the pill. It's not that she's encouraging it its just she knows I'm sexually active with my boyfriend of almost 3 years and because my period is so irregular.  By irregular i mean seriously irregular, since last summer I've only got it 3 times once for 9 days then for 3 and then for 5 days.
So really I'm just wondering is there any side affects of going on the pill? I do want to be able to have children when I'm older so will this affect it?