The symptoms of breast cancer is basically an abnormal growth in your breast or armpit area.
The chances of a 14 years old getting breast cancer are extremely rare or completely unheard of, i do not think you should worry at all unless maybe a very close relative suffered breast cancer at a young age such as your mum or aunty or grandparent.
You are probably just goign through puberty. You breast will be changing and growing and feeling a bit lumpy in places.
The chances of breast cancer at 14 are very close to zero.
It's almost unheard of in under 20s, and in fact fewer than 0.1% of all those diagnosed with it are under 30 and only 5% are under 40. Most (80%) are over 50.
When I was diagnosed with breast cancer I was classed as 'young'; I was 50.
The American Cancer Society and other cancer organisations recommend that women begin breast self examination at the age of 20. Before that it's pointless; firstly because there are so many hormonal changes that there is no 'normal' - and self examination is about a woman knowing what's normal for her and reporting any changes. And secondly because the chance of breast cancer is almost nil.
At your age your breasts are still growing and developing and any breast changes you notice, including lumps, are almost certainly hormonal and perfectly normal.
Early breast cancer has no symptoms; there is no need for you, at your age, to be concerned with the possible symptoms of breast cancer, but I'll tell you what they are because you can find them by googling anyway.
change in size; one breast may have become noticeably larger or lower
nipple change; if it becomes inverted (pulled in) or changes its position or shape
rash; on or around the nipple
discharge from one or both nipples
puckering or dimpling around nipple
swelling in your armpit or around your collarbone (from lymph nodes)
lump or thickening that feels different from the rest of the breast tissue - but remember that most breast lumps are not cancerous
constant pain in one part of your breast or in your armpit = but pain is rarely a sign of breast cancer..
Talk to your mother about any worries you have; if you're not comfortable doing that, talk to your school nurse; she will be used to girls having worries like this and will be able to reassure you that you don't have breast cancer