Chemical vs miscarriage

Help!! I'm currently going through my 4th loss in our journey to conceive our first child. 3 of the losses have been before 4.5 weeks so I guess they were chemical pregnancies. The other one was at around 9 weeks.

I know a loss is a loss, but what about medically??? Because 4 miscarriages sounds worse than 1 miscarriage and 3 chemicals.

So when does a loss count as a miscarriage medically? My hubby and I have been tested for everything under the sun by the doctor and they couldn't find any problems.

What do y'all think????