I Was Previously On Escitalopram 20 Mg But Had Issues

I was previously on escitalopram 20 mg but had issues sleeping. I was switched to 30 mg of mirtanzapine but I felt as if I had lost all of the beneficial effects of the escitalopram. I am now on 10 mg of escitalopram and 15 mg of mirtanzapine daily but I don't feel like I am quite were I want to be with my anxiety levels. Can I increase the dosage of my escitalopram to 20 mg like before and keep the 15 mg of mirtanzapine to ensure a proper rest? Just inquiring if the dose can be increased while taking 15 mg of mirtanzapine.