Hi dani! Your cramps could be associated with implantation, but many women do not feel this. However, your bleeding seems way too much to be implantation bleeding. Impl. Bleeding usually only occurs for one day, and it is light red to brown in colour. If you are still bleeding today, or it has been heavy, then I would assume it is your period. B/c you have irregular periods, you say it is "too early" for it to be your af, but that's just the thing with irregular af's....You never know when to expect them!
I would wait a few days, see how you feel, and you could try taking a test, but if it comes out negative, try and wait to see what happens around the 7th of jan (when you said you were expecting next af) and then take another test. If it is still a bfn, and you are still not feeling well, or are experiencing some pregnancy symptoms, call your doctor and get in to see him/her.
Good luck and keep us posted!