Where is the line between normal worry and crazy paranoia?

I worry a lot about strange things for example my s/o is out of town for 4 days so its just me and my son at home. I debated for about 45 minutes if I could step out into my yard to smoke a cigarette because I was worried I could be kidnapped and my son would be stuck inside the house without water and get severely dehydrated since no one would know to come find him. Then debated filling several cups of water and leaving them around the house just in case… (legit knots in my stomach fear about this scenario) So I texted my sister to come to my house to save my son if she didn’t hear from me in the morning.

I have these types of thoughts and irrational fears several times a day about random routine activities.

When is being paranoid beyond normal?