Haha your fingers will hurt more when you play acoustic guitar, rather than electric. In any case, it's natural for fingers to hurt after 3 months! Your fingers will still hurt even after a year of playing :)

The trick is to not press down very hard on the strings - just BARELY enough for them to sound. Pressing harder won't change the volume, unless you are trying to perform some kind of technique, like a bend or slide or whatever

Here's how you test to make sure this happens correctly:

1. Rest your finger on the string, without pressing down.
2. Start picking that string with consistent 8th notes, with your pick.
3. SLOWLY press down on the string, until you can hear it.
4. Let go very slightly until you can't hear it. Press down a TINY bit more until you can.

that's the perfect spot to press down! Any harder will only be spent energy that will make it harder to relax after playing the note.

Let me remind you that it's only useful if you're playing chords, or a single note, or a string of notes. If you're using a technique, you should use as much power as you need to execute the technique.

Remember also to completely relax your finger after playing each and every note. Play-relax-play-relax-play-relax. You will have to play very, very slowly to do this in the beginning, but this is how virtuoso players develop their insane speed of 1000 notes per minute eventually. They are totally relaxed when they play :)

Hope this helps!