Simple financial modelling sales predictions based on current years sales job (excel)

Problem: I’m looking for someone who is available immediately to work on this today. I need some help from someone who has good experience in both excel and financial business modelling to help predict customer sales for the year going forth (Feb ’19 – Jan ’20). We have three income streams - Two of these streams have unlimited sales potential - The Third stream is limited in the amount it can increase by. Sales of the third equalled 70% of capacity in the last year. So we can only increase those by sales by a maximum of 30%. There are some variables we need to take into consideration, because we are scaling our operation. Number of active email marketing subscribers - New registrations - Unsubscribes Seasonality - we’d like the forecasts to take into account seasonal fluctuations - but this is difficult because number of subscribers varied through last year Recruits - we are increasing our database by 16,000 customers monthly. - So predictions made for sales need to cumulative on that basis. I’ve gathered much of the data, but I’m having trouble creating the correct formulas etc, to extract the figures I need. Imagine this is quite a quick job from someone who has done this before. My original thought was to base all of the sales on last years, then use the % increase in customer database size to calculate sales on a cumulative basis, and then take a sum of those sales and then divide those sales back into seasonality fluctuations which we observed in the previous year, but I’m unsure of whether this is the way it should be done. Objective To add in the correct formulas to properly and explain the logic to me in simple terms so that I understand the correct way to model these predictions. I have a file ready with the data you need. I think budget around £50 is good for this job, I think it's probably 1 or 2 hours work for the right person.