Oil light CITROЁN

Hi, recently I have seen that my oil light comes up when breaking but when driving it was ok. Then this weekendom the long trip it started to worry me more and more. As onetowym motorway it was okey, however in the city the alarm was constantly on and off. I already once had a car with to much oil so I’m hesitant to put more oil in. I have tried to check the oil level but I’m not sure if I’m doing it right. The engine was cool but on the incline (engine lover) and I moved the car few meters for flat surface and then check. The fill is attached. Please, could you let me know what should I do?

A bit of history of the car.

The MOT and full service was done in April.

In beginning of August the stick gear feels very stiff when start driving.

In middle of August the exhaust box was changed.