Looking for help in calculating Sharpe

Hi all,
I'm an intern at a fund and I'm trying to calculate the sharpe ratio for a hypothetical portfolio consisting of 3 different ETFs. I'm using excel and coming up with a sharpe of 0.06, which seems extremely low - most likely due to incorrect calculations or using wrong numbers. Would anyone be able to help me with this?

Thanks in advance!

Here is how I did it (formulas) - I am unable to post links.
1. Cumulative return of ETF: =(latest price (July 2020)- initial price (Jan 2015))/initial price (Jan 2015)
2. Annualized return of one ETF: =(1 + cumulative return)^(12/61)-1 [61 is the # months of data used]
3. Overall portfolio annualized return - I first found the weighted annualized return: =weight x annualized return
then I sum it together to find portfolio return: =sum(weighted annualized return)
4. Standard deviation, using daily return (=(today's price - yesterday's price)/yesterday's price), then to find monthly returns: =STDEVA(returns column)
5. Correlation: =CORREL(price column of ETF A, price column of ETF B)
6. I found the formula for a three-asset portfolio standard deviation online, which consists of 2 parts:
First part: Sum of weights squared multiplied by standard deviations of each ETF squared
Second part: Sum of 2 x (weight of A) x (weight of B) x (correlation between A and B) x (Std dev of A) x (Std dev of B)
Taking the square root of the sum of both parts gives the standard deviation.
7. Sharpe Ratio: (annualized return - risk free rate (0.13))/annualized standard deviation