will it affect?

Not to worry, nothing will happen to your baby is you don't eat when you get a hunger pang. However, don't get into the habit of ignoring your hunger. Try to get regualr wholesome meals in and you needn't wait until you get super hungry. I remember I used to eat bits of fruit and nuts and other healthy(ish) snacks when I was hungry. Also, there's absolutely nothing wrong in feeling hungry all the time when you're 7 months pregnant. This is very normal.