First of all you should know what actually a fibroid
Fibroid uterus is a benign tumor
which is oestrogen dependant and can occur in any part of uterus- body or cervix
, anterior,posterior or lateral.
They can be submucosal, intramural or subserosal in site of origin.
They are a frequent cause of morbidity in females and frequently cause excessive menstrual bleeding
both through increased frequency and increased blood loss.
They can be solitary or multiple and their size tend to be variable- may increase or regress spontaneously.
You have a quite small fibriod and i don't think it should be a cause for excessive blood loss or pain during menses. It is possible that it is the pain of menses as such which seems to you related to fibroid since you know it is there.
I have a good news for you- Fibroids tend to decrease in size and are less troublesome during pregnancy
and I hope that size of fibroid will never cause any problems.
Sometimes when fibriod is large, may undergo Red degeration during pregnancy and may need to be managed with hospitalisation but that's a rarity.