4dpo and getting twinges

Not sure if I've ovulated as I don't track but had a hsg at the end of last month and I'm currently 4dpo and for the last two nights I've being having weird twinges not sure if I'm pregnant or not. Have irregular cycles as I have hypothyroism and overweight. But I've heard that after a hsg your very fertile don't know how true this. 
Any advice would be appreciated