I can't help but think that I made a mistake by not investing in weapons first. From my observation, investing in weapons first give you more potential in disabling ships (pvp) and thus gaining red badges more quickly to buy those dominion cannons which in turn increase your potential further due their good attack/deck ratio. Right now I'm lvl 50 focusing more on cloak and scan and when I decide to improve my weapon/attack strength by going for dominion cannons I realized that I'm outgunned by most players in my range simply because they already have some dominion cannons which gives attack for less space than conventional weapons. So, am I stuck being the weak player here?

You're not stuck, Just target the guys that look sqimish, and take off cloak/scan, and add HULL and WEAPONS (Maybe a def mod when you get space)

Attack is awesome, I love it, but a few carefully picked targets on the BT can make you enough reds to get the doms...

I don't know. I equipped 4 light disruptor and 1 crimson auto-laser which takes half of my max deck and I still have trouble disabling ships. Worst still, my upkeep goes through the roof and the repair cost is not cheap either. I can't help but to think I'm going bankrupt before even gaining my first dominion cannon.

you should be able to ask your legion for help with expenses until you can get more mining planets...if not , they suck and you need to find a better legion

i would say shift all of your research into weapons until you match/outgun players your own rank. Try to slow your leveling a bit when you do this so you dont zoom through the golden ranks of pvp. Until then, go max cloak, so you dont get found on the bt... then, once youve researched and can install 5-8 guns, remove your cloak when pvping, kill some players, and then reinstall your cloak to hide. Then, once you get the dominion cannons, you can install those, and hopefully have an insane combat rep by then, and drop a bit of cloak. As for having scanners on your ship, i wouldnt recommend having any researched scan tech on your ship until you are a bit more deck heavy. I have 4016 decks, and still only have one scanner installed.

I found that having a mere 209 attack was enough for me while I was collecting reds for dominions. You just need to be patient, and not waste your energy on people with thick hulls. (I'm 58 with 723 kills, 552(+ a bit for mistakes) of those were with 209 attack). I'm not encouraging you to neglect gun research, because once you have pvped, you'll need those guns for npcing. I'm behind on those, only in middle of sing launchers.

The problem with researching better guns is that they become too expensive for me to buy and maintain. Then, I can't really tell every time if an opponent has thick hull or not due to my reduced scan. Removing and reinstalling modules requires cargo space that sadly I don't have enough.

try to get 5 singularity launchers on your ship by rank 100, and dont bother with scan at all, and just run with 1 cloak. that was my build at that rank, and i would get 20 kills+ on a pvp run. When i say a run, i mean without repairing. now, i can get between 3 and 7... but yeah, your build is a missions only build. cloak and scan really serve no purpose except to hide. And if youre so short on credits, go builder. Its something you want to avoid at all costs, considering its like sillix, once you have it, it just gets harder as you progress to switch race/profession. If youre already builder, then i would suggest getting more mining planets. I know, its obvious, and may be difficult, but you sound like you have decent scanners. Try to get a continuum beacon, a stryll seeker, and the other two hard value ones. Put up all 5 scanners, and then with a full bar of energy, do a scan run until either you run out of energy, or you literally cant perform another scan (less than 5% chance to scan another planet). This will give you probably 100 planets to pick from. Try to stick with either very large volcanics, or large/larger toxics. These are the primary mining planets in the game, as toxics can be improved up to 15/16x, and volcanics can be converted to demon planets. If you can, switch your invincibles to primarily mining. Remember, all you need is enough to make upkeep, and maybe 20% more for repairs.