The 21-year-old suffered widespread criticism after a string of early mistakes at United, but has since established himself as a regular start under Sir Alex Ferguson, and the Spaniard believes he is finally beginning to get to grips with the Premier League.
"My English is getting better," De Gea told the Guardian.
"I understand most things but I find it harder to speak. English football is different, especially for a goalkeeper. It's more aggressive, more physical. It's far, far harder. The ball is in the air more and you get pushed about. And the referees don't blow [for] anything!"
De Gea's slender physique was often touted as a factor behind his shaky start, whilst others have pointed to his eyesight, with the club even recommending he undergo laser eye surgery to improve his visibility.
However, the shot-stopper is confident neither issue will prove problematic to his development at Old Trafford.
"Eat well and lots of gym work. We're not talking about a huge amount anyway: just four or five kilos. The other thing is that I am still young and I will naturally fill out anyway.
"I'm just short-sighted, like loads of people. I wear contact lenses - in fact, I've got new ones - and I can see perfectly well, just like anyone. I don't understand the fuss. I put lenses in and ... perfecto."
De Gea will feature for Spain at this summer's Olympic Games, having come through the ranks of the World and European champions, and the youngster insists that he has never doubted his own ability, but admitted being aware from his native country has proved difficult.
"There have been doubts in the first season but I always had faith in my ability. The pressure at an elite club like United is huge but Ferguson just told me to do what I did at Atletico. You have to be as strong when things go wrong but I don't get nervous. Mistakes are normal; everyone makes them," he added.
"I think that at times people don't realise that it's not easy. You travel a lot, you work hard. When you come home in Spain, your family are waiting for you. When you're in England, they're not. For a Spaniard it's different.
"What are the worst things? From a Spaniard's perspective, it rains a lot, it's cloudy, it gets dark very early, maybe you're a bit bored. The winter can be hard: playing over Christmas is a big change. The food: it's not bad but it's not the same. You miss friends and family. People don't always appreciate that. There are hard moments.
"But those are the sacrifices you have to make to keep on growing and to improve as a footballer. And when you play, when you go on to the pitch, when you hear that atmosphere, when you play the game, that small sadness gets washed away. And then you're happy."