There's actually a lot of players who disrespect + frame moves. Top players included if know their advantages/disadvantages. They're taking the risks of being frame trapped, but in this case, they don't care. They either don't know, willing to take the risk or don't care about your advantage because you're not doing what needs to be done to stop them. You have to be the one who stops it by frame trapping them. If you're not making the adjustment of frame trapping them, then that's on you man. Why should they stop doing what they're doing when you're not adjusting? Just like why should you stop frame trapping or meatying players when they keep hitting buttons?
Could be online latency too.
Also, Sazbak said this earlier, but Supergirl's 112 isn't +3. It's +2 with the adjustment that they did to it. If it was +3, then her d1 (9 frames), would end up being 6 frames, but it ends up being 7. 7 framers trade. So characters with a 6 frame low can still poke her, but you can backdash then whiff punish, neutral jump then nj3 (in the corner), special cancel like mb breath/down laser/bf3, or frame trap with b1, f2, or standing 2. Her frame traps varies now since d1 got nerfed. You have to see when she can use it properly against each character who does/doesn't have a 6 or 7 frame mid or low. They probably knew that, so they kept mashing you out. Have to condition them in d1s now. The nerf does suck since it's not a completely reliable poke, but it is what it is. Either way, the issues that you're having can be fixed assuming that it wasn't online screwing you.