I honestly didn't have any notable symptoms of PMT or anything before having DC - mild period pains and some spots at worst.
After having DC1 I noticed the pains were worse and I became more conscious of changes in my sex drive throughout my cycle.
DC2 has resulted in periods every 6 weeks, the first couple of weeks I feel light and motivated and lose weight easily, the last couple of weeks I have constipation, bloating, I feel lethargic to the extent that I am drowsy and cold and I am paranoid and irritable.
It can't always have been like this or I'd have noticed, surely.