Okay, I’m sorta in the same position, I’m stuck with no idea where to go. When it comes to weapons I think the next step is adding forma, primed mods and riven mods, with warframes I’m still in the blue with what to do next. With what builds you should be looking at, you’ll want a warframe for anything, spy, defence, extermination, and what’s sorta known as a rainbow build. For a spy build you want a stealth warframe, one that can go invisible/make areas invisible like Loki or ivara or ash. For defence you want warframes that can create choke point or stop or reduce attacks at the defence point like gara or frost or khora. For extermination you want warframes that can pump out damage quickly like volt or Garuda or nova. For Rainbow build you want warframes that can do a bit of everything, kill fairly quickly, defend points and such, almost any warframe can do this they all have some sorta defensive and offensive skills. If these aren’t you play style and you’d rather support your allies, crowd control is always a nice helping hand, warframes that can manipulate the enemy to fight for them, or stop attacking you and allies, disarm them like nyx or Titania. Or just straight up heal or buff you and allies like trinity or Harrow Valkyr
The main idea is to try out different warframes and find what play style you prefer. Personally I play nyx as I like crowd control, but that’s not for everyone. Each warframe will do something different and change how your squad works. Try as may warframes and weapons as you can and find ones that work for you and don’t let people tell you that you can’t play that one cos that’s not the “meta”. You play who and how you want and just keep trying new frames even if they seem daunting or boring, they might become your main one day