I did some research and this seem to be very common. I don't know what to do help me please

A period this long could be due to many things such as weight issues, hormonal issues, post menopausal atrophy, a cancer, a polyp or a fibroid - but you said you have periods - so you are not menopausal.
So, you do need to get this evaluated and I would recommend a pelvic exam, plus also checking your thyroid too as thyroid problems can cause bleeding problems.
Thank you