I have been in a similar situation, less modes of contact (post, text, whatsapp, email, phone and in person) but i did spend a lot of time trying to remember when, where and how people contacted me and what things I had to do… (caveat I was in charge of a department in an organisation, rather than it being my own business)

Assuming you don’t have any spare pennies, or underutilised resources at your disposal to delegate… Some practical things I did…maybe it will give you and others some ideas.

Tried to change how people corresponded to me – I finished so many phone calls with the words… “Would you mind emailing that to me, please?”  Or after a conservation in another office or a meeting “You’ll need to email that to me, or I’ll forget”, when I met someone, always told them to email me.  Email worked for me, as I can type quicker than I can text, and it give me a paper trail plus it is so easy to search.  I would have even emailed replies to text messages or missed phone calls if it was possible.  If I ever get business cards again, it is only going to have my email on it – if you are important enough, I’ll write my number on it (or if you are cute 🙂 )

Paper and pen – nothing beats an old school phone book… if you can get into the swing of it… saved my balls a few times – especially when batteries or phones die!  I also kept it in the same place, so I didn’t lose it.  Also a big fan of to do lists – if something was on the list for more than a week and you weren’t busting my balls to do anything about it, or it wasn’t really important it got wiped. To do lists were the only thing that kept me functioning as I just had masses of demands and information hitting me at the same time.  Also if you are walking round with something in your hand (like a notepad or piece of paper) people will think you are busy and are less likely to talk to you (top office tip!).

Had two phones – a work phone and a personal phone.  Very few people I worked with had my personal number, can’t recommend that highly enough to people – no-one had my personal email address or social media.  I would have even called back from my work phone if someone from work rang my personal one… Full separation between church and state.

Plan in quiet time – I tried to get an hour a day that I could get on with things without being disturbed, even if it meant going in 30 minutes early (and taking back that time when things were quiet).  Woe to you if you came into my office when I was having my quiet time!  I also called Friday – Fuck off, Friday – for some reason less people annoyed me on a Friday but that could just be a coincidence.