Implantation Cramps And Constipation?

I have recently been TTC. My periods are irregular (last two cycles were 39 and 42 days!) so its difficult to map out my cycle. However normally I get symptoms of ovulation around the day 14. This cycle I think I ovulated on 21st May and I had unprotected sex everday leading up to and past this day. 8 days later I had some really sharp stabs in my uterus area. Ovulation is normally on one side whereas this was in the centre. It was a throbbing pain and lasted a minute or two. Ever since I have had what feels like period cramps and I have become increasingly constipated, its too painful to push which I normally get on my period. Sometimes its too painful/uncomfortable to sit down. It is now 12 days from when I think I ovulated and I have had the cramps for 6 days. I have had no other symptoms. Took an early test but it was negative, so I assume the HGC hormone isn’t high enough (if I am pg).
Does this sound like early pregnancy symptoms? I know all women are different but if any of you experienced this as well I’d love to know about it and also how to deal with the constipation and pain…