Contractions

It’s my first pregnancy and I’m 29 weeks. So my question is, is there a way to explain how contractions feel ? people tell me when they come I will know but I’m hoping some one from their experience could explain what it feels like more or less and where they felt them. Is it the top of my bump ? The bottom ? Whole bump ? Is it like period pains or stabbing pain ? I’m very anxious and scared I will feel some pain and think that it might be from being tired or it’s just normal to feel discomfort towards the end. Any help ? (And no judgment please)