Could it be implantation bleeding?

I have been TTC for three months and so far no joy! I started getting cramping pains on Saturday and generally felt like rubbish so thought great, I'm getting my period. The cramps lasted all day Sunday as well and into Monday. This prolonged cramping is not normal for me. I have been off my pill since January to give my body time to adapt to being off it before TTC and so I know this prolonged cramping is not normal. I started to bleed on Sunday also - cramping plus bleeding led me to believe it's just my period. I was like clockwork on the pill but since coming off I have a cycle anywhere between 27 days - 36 days and so I can never 100% say I am definitely due on at a specific time. My period normally lasts 5 days and Indo not normally experience massively heavy bleeding. This period along with the cramps I have experienced particularly heavy bleeding and it has lasted just under 2 days. I went to change my pad from overnight and I had basically not bled, a few light spots. Put a tampon in this morning (I use applicators) and when I pulled the applicator out, it was not bloody (sorry to be grim) at all. This is not usual for me either. I had reserved myself to the fact this was my period and now the differences to my usual period have got me wondering what the hell is going on!? I am going to keep checking but what do people think?