eating all Calories?

I have been dieting for 7weeks and have been doing well but the past 2 weeks the weight has been hovering within the same 2 pounds mark. I have found I am also eating approx 300-350 cal under my goal, so I am going to try and see if by upping my calories to my goal this week has any effect. I think it might cos I am using the spare calories to fill a void between meal. I'm one of those people that will eat 3 meals a day, it works for me it is how I have eaten my whole life, just cant manage the effort or appetite to eat 5-6 small meals a day. So here hoping for a more productive week.

I have a huge Question? I have a daily goal of 1,970 calories and typically I am under by 400 calories each day. Should I be eating all of them? Thanks for any information!

Hard to answer definitively without more information.

Are you on maintenance calories (ie... Zero lbs per week weight loss goal)?
If no for the above question, are you shooting for a smaller weight loss ( 1/2 lb or 1 lb per week) rate?
If you're at the 2 lb per week loss goal and have 1900+ calories for a net goal, maybe check and rethink your input activity level if it's not really accurate.

The short answer is you're probably fine if it's not all the time and the calories you're consuming are high quality, as in little junk food.

As long as you are getting enough nutrition(all your vitamins and some carbs etc) you should be okay. I would not be worried about your body going into starvation mode. If you want to add more calories though, try to do it in the most nutritionally dense way as possible. For example, adding more fruits to oatmeal, including a whole avocado with lunch, adding more veggies to dinner and having a fruit smoothies with two bananas in it for dessert. This all should add about 500 more calories.