So I have a pretty decent background learning Spanish (far from fluent, but pretty good) . I travel a lot and have been able to speak to locals pretty well. However, one thing I tend to have issues with is ordering coffee, specifically lattes. My parents like to order lattes with only one shot of espresso, rather than the standard two. In America, this goes fine. However, when I order in a Spanish speaking country, the batista looks at me like I have a third eye growing, not sure if they don't understand what I'm saying or what...?

The way I usually order is "Quisiera un café latte con solamente uno trago de espresso."

Is there a more appropriate/accurate/understandable way to request this?