Beaufies so sorry for you - but you are in the right place - we are a proper bunch of rambling, frustrated, sometimes sad, sometimes happy, imparters of TMI.
Seems like you are in a place we have all been, albeit in various different circumastances.
Sounds like mc like many of us have had, brown to red to clots to cramps, its normally heavy for a week or so.
I am, like you, keen to have another dc as I have a ds and I so want him to have a sibling and if I can't because I have left it too late (am 37) will be gutted that was so selfish about starting late
Just because you have had mc does not mean no more chances at all, some women have several, young women and older women, it can be for a million different reasons and you won't know why.
In terms of trying again right away - most of us did that! Not sure if it is any different with IUI could be ..... worht asking the doctor maybe, although someone here might know!
Anyway - welcome x