Yeah it does seem that way but trust me she is really good at being herself! It takes time to get used to her and master her character as she's not very easy win with especially if you don't know what you're doing. Few things you need to know about her is that her attacks generally does not do a lot of damage which means you're going to have to pressure your opponents with an array of attacks and mix ups if you want to win effectively. Lex is VERY good at quick poking and making use of evasive attacks at close/ range i.e. 2k, AAB, 22B, 4K, 1B+K, WR B, 22_88K for starters. Most of those moves side step before landing an attack these are evasive moves that are VERY good against MOST characters ESPECIALLY characters that rely on vertical tactics. You need to try your best to apply pressure whenever opportunity arises this will keep your opponent 2nd guessing whether they should attack or not and THATS where you want them! Unpredictability is KEY is Lex you need to try your BEST to be confusing as possible using a variety of MIX-UPs to confuse your opponent. It takes a lot of practice and I know the training room gets boring but you should at least spend about 30 mins a day if not more if you really want to learn her. You can ask me whatever and I will answer as best as I can because I am still learning too.
I can see you're having a major struggle... Ok first off the ONLY move you should be doing after a 3B launch IS 3B+K, why? Because it does the MOST damage there is no other follow up that can replace that. If your not aiming to take maximum damage when possible you don't need to play Leixia she isn't for show and tell. 2nd DO NOT always add K after 3B+K and then try to attack because you're likely to get hit. 3B+K is -11 on block and if you add K its -6 which isn't much. Instead a better strat is to do 3B+K KG and mix up grabs with FC 3B or another mix up.
FC 3B is one of the BEST moves in her arsenal thats a safe negative 10 on block that pretty much NO CHARACTER can punish save for maybe Natsu with her i10 AA (still highly unlikely). There are TWO good options for FC 3B follow up and 3B+K is NOT one of them. The first follow up is 1B it does 43 total dmg and great for viable mix ups (i.e. WR A+B/ 3B or Grab/ mix ups) since the 1B slams the opponent down to the grown leaving her in crouch position they will have to guess which her next move is because there is SO MUCH she can do from an FC 3B, 1B. The next and most damaging move after FC 3B is 6A+B. It's not a mix up set up but it does THE most damage after FC 3B which is a total of 55. So if you're going for the fast kill (which you should be) this is the move you want to follow up with.
Lex 3 Brave Edges are AA BE, AA BE K, and WR B BE. The only one you would want to use the most is WR B BE because it side steps before attacking, it impacts and its safe being -6 0n block but because its a slow i31 some people may be able to step it on reaction. But it is good does good damage and leads to a possible CE. (WR B BE, B+K, CE) TRY IT!!!
Her AA BE is also good because you can hit confirm the A attacks before going into BE. By hit confirm I mean you can see if the 1st and 2nd A hits before pressing A+B+K. NOTE* AA BE will ONLY work after the 2nd A hits! keep that in mind. Though you probably will not be able to pull these off too often... YET! until you get used to her> (I'll explain in a minute) try these simple combos for AA BE
3B Wall Splat AA BE, 3B Wall Splat 4A+B, CE
4A+B Wall Splat AA BE, 3B Wall Splat, AA BE
4K Wall Splat 44[A], AA BE, 3B Wall Splat 4A+B, 66K
AA in general is a GREAT punisher being i11 it can punish the vast majority of moves. All you have to do is hit confirm the 2nd A after punishing then go into BE its that simple they can't stop it and it's off a PUNISH thats going to happen, well, OFTEN!
Hope this helps let me know how you're doing!
