Hi,
I could easily create most of the formulas you need and I could even guide you through some of them. I've worked on Google Sheets for over 3 years now and I'm willing to do the work for 20 EUR. Hopefully, this isn't too much on your budget. If you have any concerns, please don't hesitate to send me a message and I will address them as soon as I can. I would really appreciate it if I could work on this with you.
Regards,
Rich :)