Money saving app needs simple, fun, evocative logo

Spare

Young people are struggling with saving money. They don't have enough time, money or knowledge of how to do it. Spare is an application that helps millennials and young professionals save small amounts by rounding off their transactions to save small amounts as they go. They are either busy or don't have enough money to save so they just avoid it. We want to make it something they enjoy doing and don't see as a burden. The small amounts they save through Spare can then be invested or kept in a savings account. Our aim is to make things simple, intuitive, streamlined and the opposite of stuffy (opposite of style of banks, corporate, financial institutions). We want a logo that is strong and confident, while being friendly, fun and human.

Our current wireframes are using the following HEX codes but we are open to looking at other colors as well.
Color 1 : #6874e7
Blue (light blue) : #7c8fd9
Orange (accents) : #ff3c00
and white

1.PLEASE SEE MOODBOARD
2. We have already done the design for the wireframes and pages in the application but haven't been able to find a logo we like. The document attached shows different logos I like and why I like them. We want a logo that has an element (icon, letter, etc) that can be used as an icon for our application as well as social accounts.

*****We are not looking for a logo featuring the letter S as an icon or graphic - appreciate if you could avoid submitting those. Creative interpretations will be more interesting.