Triangle Wave Generation
If you are using a modern op-amp for this, I'm going to guess that your problem lies with the value of the integrating capacitor C2.

As you already figured out, R1 &amp; C1 set the square-wave frequency.  C2 integrates that square wave into a triangle wave.  But the value of C2 depends on the frequency that you are trying to generate.

Given that you said that you are only getting about 4 mV output, I'm guessing that C2 is somewhere between 100 to 1000 times too large.

You also don't mention your supply voltage - making C2 about 1000 times smaller should theoretically give you about 4V P-P, assuming that your supply voltage is high enough.

Also ensure that R5 is a very large value - somewhere between 1 - 10 MOhms.  Its only purpose to provide DC feedback to IC2.  If R5 is too small, it reduces the gain.