I don't see why you're using a 2N7000. An Attiny pin is able to drive the IR LED/resistor directly.
A TSOP receiver is meant for interrupted IR signals, like remote controls.
Are you driving the IR LED with interrupted 38kHz?
AFAIK TSSP (not TSOP) receivers are better suited for constant 38kHz.
150-220ohm for the LED (~20mA) seems a lot of power for a few centimetres distance.
You could easily bridge 5 metres with that.
R4 is not needed. All TSOP/TSSP receivers have built-in pull up (~33k).
Leo..