Where, within the range, you should best eat is highly individual. Even the ranges don't always work.
If you are not achieving success, by all means try eating 1300-1400 for a few weeks and see if anything changes.
That is an intake level that is still LOSS no matter what you're doing for exercise and lifestyle. So if you manage to actually gain when you increase, this doesn't mean it's too many calories for you. What it means instead is that you've been significantly under eating and your body is getting back to normal. If that happens, persevere for at least 8 weeks and look to increasing another 100 cal per day after that as you'll likely still be on too low.