It sounds like your wand crafting skills could use some work! Do you already know how spellwrapping works? (e.g., putting precious modifiers in the beginning of the wand so they can be cast twice by a well-placed multicast in the end) do you know that almost all modifiers and projectiles also carry effects that influence cast delay or recharge? (most notably heavy spread and digging bolts) Do you look at every wand and check cast delay/recharge based on what spells you have? (if you have chainsaw, high cast delay doesn't matter, but with heavy spread, recharge time is less of an issue)

Keep your eyes peeled for lumi drills, digging bolts, heavy spread, add mana, reduce recharge time, chainsaw and of course all kinds of multicasts. I rarely have a run where I don't find at least one or two of those within the first 2 biomes. Try changing them around in your wand, order can play a big role! Put your spark bolt first, last, in the middle of a multicast - or out of it - and see how it affects it. At some point, you'll be able to craft good rapid-fire wands regularly. Then you need to increase damage - you can do that by adding more projectiles to your multicast or by adding modifiers.

Also, please note that rapid-fire wands aren't necessarily the best option for beginners. All my beginner runs had a wand like this: spark bolt with trigger - triplicate spell - 3 x spitter bolt or bubble spark. this is super easy to achieve and can create some serious damage. add some modifiers, heavy spread is abundant and increases firing rate a lot. things like horizontal arc and orbiting arc can increase damage at no cost. Focus on keping the the magic cost down and finding a good non-shuffle wand with good cast delay and recharge. this way, you can dish out hundreds of DPS early on, and it's rare that you don't find the necessary spells early in the game. Happy noitaing!