Portable breast pump necessary?

Any reviews on baby express (or any other) portable breast pumps? I alr have S1 & considering to get a portable pump so that I can use it whenever I am out with my first child. But I’m not sure if it’s worth to even get a portable pump because my yield is not as much (even feel like giving up now , it is just my third week w a newborn 😭) Idk why the supply jus wouldn’t cross over 100ml (combined) each pump sesh ☹️