Period help !!

For the last two - three months I’ve noticed my periods are becoming 2-3 weeks later than expected... this is weird because my body was ALWAYS in tune with my periods and they were only 2 days late Maximum. Now when it comes around for my period, it’s like my body doesn’t even feel the cramps come on or I’m not even expecting a period. I’m 19 and when I first noticed this I thought it was pregnancy but I done the test and stuff came back negative then my period came the week later. Today I’m meant to be on my 3rd day of my period but it doesn’t even feel like I’ve got it on the way. I’m very worried and scared of going to doctors about this Incase this is something serious but I will refuse to go because of anxiety. If anyone knows this is normal or not please comment- If it helps I am healthy weight although during the pandemic I put on a couple pounds so perhaps it’s weight that’s thrown my periods off?