adding jquery at the very bottom
You need to set a dependancy on your library definition. e.g. if you want your custom.js after geofield then in the library you define custom.js you need to set a dependancy e.g.:

mylibrary:
version: VERSION
js:
  js/custom.js: {weight: 0}
dependencies:
  - geofield_gmap/geofield_gmap