High heart rate & anxiety

Hello all! I wanted to share my recent experience, and ask if anyone has gone through anything similar.

I have been on 60mg Vyvanse per day for several months now (40mg in the morning and 20mg in the afternoon). A few weeks ago I began feeling off in my body on some days. A couple days a week I would feel very anxious and could feel my heart beating fast. At certain points it would reach 120bpm sitting still.

After googling it and freaking out, I decided to reduce my daily caffeine (from 4 cups to 2) and brew my coffee twice as weak. I also went to the GP to refer myself onto a quit smoking programme. So yeah, I am a smoker too, and I also use bloody nicotine pouches.

It has all started to make a lot of sense. Combining 3 different stimulants should obviously raise heart rate and cause anxiety. However, I can’t quit caffeine and nicotine cold turkey, because the medication becomes less effective. It’s probably only a short term problem, I understand, and should probably boost its effectiveness once I’ve dealt with those addictions.

In the meantime, does anyone have any advice how to go about navigating this situation? I still feel strong urges to consume more caffeine and nicotine alongside my medication, and I know that it isn’t being tolerated well by my body. Thanks for any suggestions.

P.S. does anyone know of any possible reasons I could be experiencing more potency for my medication? Perhaps there are other dietary or lifestyle reasons the body is processing the chemical slower? For instance, the chemical might be staying in my system longer than it was previously.