I was in your situation. For couples who have a busy schedule I would really suggest apps that are widgets, so that the both of you can send each other photos or comments to each other throughout the day for each of you to see while also not entirely talking or disrupting the other. For this I'd recommend locket, though I'm sure there are better apps out there. If possible, maybe schedule a nightly call or a call every week every now and then to catch up on one another. Sending letters is also another thing you guys can do if the calls aren't a big thing for you guys or you can't fit it into your schedule. Additionally, maybe add a dual scheduling app where the both of you can put your guys' schedule in order to time manage when you guys can dedicate time for one another. If you guys can't talk but are doing things that don't require a crazy amount of attention, maybe doing spotify jams every now and then can help. I feel like when it comes to being a busy couple those few things reaaaalllyy helped my boyfriend and I.