Why do my margaritas always suck?

I don’t drink. Well, not really. But I like to make drinks for my friends. But there are 2 cocktails that I find good enough to actually drink for myself. Bloody Mary, which I whole heartedly believe I make better than 95% of bars/restaurants, and Margaritas, which are simply the most delicious alcoholic beverage on the planet.

My question is, as you can see in the title. Restaurant Margs blow mine so far out of the water it’s not even fair. And I don’t know why. I follow the recipes to a tee. Well, for one exception. I use triple sec over contreu. Is it possible that it makes all the difference?

Or is the difference that these restaurants are using mixes that have a lot of sugar or corn syrup added, giving them a level of sweetness I can’t attain with the old fashioned ingredients?

Just for reference, I do the classic tequila, fresh lime juice, and triple sec, salt. And boy is it always bitter, and boy is it always strong. And I’d prefer if it were neither.

What am I doing wrong?