Did levo help those of you with tachycardia/fast heart rate/palpitations?

I have hypothyroidism and hashimoto’s. It took a long time to be diagnosed because I was told I just have anxiety. My heart rate is elevated very often (120+) and doing small things like going up the stairs makes it even worse. I’m currently on 75 mcg levothyroxine and my TSH is still elevated at around 5. I likely will increase dosage after seeing my doctor. I have noticed though that my resting heart rate since going on levo seems slightly better at around 85 recently. I still have tachardiya/heart palpitations but it’s not as frequent as before. I have had holter monitors, multiple ekgs and a heart echogram which all came back normal. My doctor refuses to believe it’s related to hypothyroidism as it typically causes a slow heart rate. My iron, vitamin D and Vitamin B-12/folate are all optimal. I’m wondering if anyone had a similar experience and if getting on the right dosage of levothyroxine helped.

My free T3 is 3.9, free T4 is 1, TSH is 5.24