I'm so sorry OP. If products get stuck in the cervix, it can cause a great deal or pain, bleeding and contraction like pains. The Dr would have removed whatever was stuck. Your scan was done at 12 weeks, but did they say at what age growth stopped?
Sorry if TMI, but if you soak the products in saline or salty water, clots will eventually dissolve into the water, whereas products will not. You can get a sterile pot from a pharmacy, keep in the fridge and when you get seen by EPU, ask for testing. Unless its your 3rd loss, they won't do genetic testing, but might go basic histology. They did this in my 2nd pregnancy loss and although didn't provide genetic reasons, did provide some reassurance/confirmation that I had indeed been pregnant and it was a molar pregnancy etc.
I'm sorry the Dr you saw seemed dismissal. TBH, she may not have worked in gynae before, nor seen an/many MC's, so may not be familiar with looking at products. In terms of 'what stage you are at', well, it doesn't follow a text book and without a scan, she'd have little idea really. I've lost 3 and all were very different in terms of pain, bleeding, what passed first etc.
If you are still soaking through the hospital maternity pads and clothes- I'd go back to A&E, as it sounds like more products are stuck. I'm sorry you are going through this, but happy to answer any questions if I can help x