The 22-year-old England international has yet to score in the Premier League for Pompey and was denied a first strike against Manchester City by the inside of an upright.
However, the former Preston North End frontman told The News: "That's just the way things are going for me at the minute. My luck's just not in and when it's not in, the goals just don't come for you.
"It's disappointing, but I'm still confident in my ability. It won't get me down.
"Unfortunately, it's just one of those things. It feels like if it was any other striker, it would have hit the post and gone in instead of going for a corner.
"I was running away towards the corner thinking it was in, but then I saw it clip the bottom of the post, roll along the line and go out. I just couldn't believe it.
"I've had a bit of trouble settling in. It's not nice being away from your family and being all on your own, but I'm getting used to it a bit more now.
"I just hope I can get another chance soon and hopefully get a few goals."