upon starting in the morning, the steering is soft and smooth, but after driving for like 15-20 mins, it gets harder to move, and starts speaking when I turn in any direction, then when the car is cold again or I turn it off and then turn on the car, it gets harder again and squeaks when I turn.
I have checked the PS fluid, it's on the mark.

The guy I bought the car from, said there is a minor leak, but after 2-3 months, the fluid is like a little bit less, hardly noticeable. I don't think a leak would cause that, what else could be the case here?

 

Fix your leaking pump then come talk to us.