According to glow my next period was due 25th but my period arrived yesterday the 21st which is pretty normal for me. I am very regular, my husband and I have been using condoms for contraception for 8 years and so I know my periods very well. We started TTC last month and this period is so unlike my normal periods... I am always very heavy and this period is very light, I wouldnt say as light as an implantation bleed though? I'm very confused! Any ideas?