Congratulations!

This was a stim cycle, yes? They obivoulsy feel your ovaries will produce enough progesterone without the crinone.
On my successful stim cycle I had some progesterone support in the luteal phase (pessaries) which I stopped after my BT. All was fine.
I had to take progesterone and other stuff for longer with my last cycle because that was an HRT cycle so all hormones were replaced until the placenta took over.
Anyway, it sounds fine and normal to stop. They'll be doing follow up blood tests I presume to ensure that your progesterone and other hormone levels are right. Some women need to take more or for longer, but usually not with this sort of cycle (as I understand it)

Cramping is very normal in early pregnancy, it can be quite painful and feel like your period is coming on. Let you clinic know if you have any worries and they should be able to reassure you.