Only spotting after last period was two weeks late? Is that normal

So last month my period was nearly two weeks late (it's usually on the 15th but it didn't rear till the 30th). I blamed stress and new jobs, new apartment, etc. This month the 15th is here (my normal time) and I'm spotting. I will preface it with I've been taking more vitamin C than my body is used to currently fight a UTI, I did have sex on the 12th but we used a condom AND he pulled out and checked the condom (we always do that for the last four years), that was the first time we had sex on over a month due to a busy life, and it's been a super stressful month moreso than ever because of work and home stuff.

But why the spotting? Is it normal for your body to try And have a period at the normal time after it was late two weeks the last time but not really be there? All the hormones are also there which is what tipped me off that I thought I was gonna have my period.