Early pregnancy symptoms - differentiating from PMS?

I've been TTC for 3 months - went of BC and got AF 30 days later, and have been regular since. I've used glow to track PMS symptoms like cramps, spotting, sore breasts etc. I'm CD 27 and this month my symptoms have been slightly different, and have occurred several days earlier than normal. Just curious if others have had similar experiences when it was still too early to test? Do your PMS symptoms ever vary in nature or timing and how do you differentiate btw early pregnancy and PMS?