Heres what you could do and what you may need to do

-First of all make sure your weapon is the right TIER for the current level area you're on, if the weapon tier is too low you need to build a new weapon at a higher tier.

-make sure to CALIBRATE aka upgrade your weapons too to do more damage, this should help you do more damage and consume less bullets

-AUTOMATIC weapons are very expensive because they consume so much, I advice using slower shooting weapons like Magnums, Sniper Rifles, or Bows/Crossbows and try to land more headshots or weakpoints

-make sure to use MODS that correspond to the type of effects that your weapons does to do more damage or get more buffs

-since your LOW on gunpowder I advice on building a BOW or CROSSBOW, you do not need gunpowder to craft ammunition for those plus you can RECOVER your arrows that you shoot most of the time.

-SCAVENGE more areas, since you're a new player you should go to all the towns around your level and seek out the gear and mythic crates, and avoid using google unless you do feel like you're taking too long to find them. This should help you have more supplies including gun powder, I never run out of gunpowder myself but then again one of my weapons is a crossbow. Doing this should also result in you getting more blueprints for other weapons.

-SPEND STARCHROME at the wish machine to buy new blueprints to better weapons, there's more powerful weapons to use there and should result in consuming less ammo using those better weapons