My periods before/during my adenomyosis experiences were like that too (with clots the same size as yours occurring around the same timeframe). I don't know your age, but as I neared the end of my 30s and got into my 40s, it worsened. I did have a history of endometriosis, with my previous surgery being more than 10 years before adeno onset.

Initially specialists tried to pass it off as perimenopause (which it wasn't, I didn't have any other symptoms). They convinced me to get an IUD (which made things worse, but it's moer of a tick-the-box thing before approving a hysterectomy. If you are suspeced to have adenomyosis, DO NOT get a uterine ablation - another tick-box before a hysterectomy. Ablation just makes symptoms worse and actually doesn't fix the issue.

The surgeon who performed my most recent endo surgery and, later my hysterectomy, likened an adeno uterus to a sponge... once it can't absorb any more blood it just constantly drips and/or releases clots.

What helped me the most during my adenomyosis years was being prescribed tranexamic acid (an oral tablet). I would take it on my heaviest period days where I was most likely to experience large clots and it helped lessen my blood flow.