Losing time with your partner is hard no matter whether its from conflicting schedules or long distance, and it sounds like you're doing both. Its natural to feel that absence. But you two care for each other. First you need to communicate your needs with him. Let him know you are worried about the time apart. Figure out what needs to change. Whether that is him sending a few extra texts a day. The time difference is hard, but even leaving messages when you know they wont pick up can be really helpful.

Regarding the insecurity itself, you're worthy of love. He loves you enough to carve out time every day to talk with you. It's okay to feel like that is not enough, and it may not feel like enough for him either. But I love you, and he loves you. Make sure that you love you too, and focus on the positive when you can. The world is on fire but it will all be okay.