After some advice / reassurance / anything 
DD is 15 weeks old, I wouldn't describe her as the happiest baby, she screams in pushchairs & car seats so I've always struggled to get her to nap. She was initially breastfed but we switched to combi feeding before going to fully bottle fed due to being convinced that the breastfeeding was making her very clingy (it took 4 weeks for my partner to be able to hold her without her screaming) but nothing really changed to be honest.
She's always been a massive sleep fighter but the last 3 weeks have been HORRENDOUS, she can now only nap for 30 minutes maximum and I can't put her down for a nap otherwise she'll wake up, she's super restless when napping (presuming she's not getting into a deep sleep) and is now waking throughout the night being restless. We've had to swaddle her at night otherwise she never slept as was constantly attacking her face. I've managed to get her to finally take a dummy however she has learnt how to take it out. She is so miserable everyday and I'm genuinely embarrassed to go anywhere as she looks knackered and I look like I'm depriving her of sleep!
Currently she is rocked to sleep with white noise playing the whole duration of her sleep and a dummy but it takes soooo long to get her to sleep for her to wake up 30 minutes later still tired.
I know it's likely that this is sleep regression but there must be a way that I can help her to settle.
I've been reading into sleep training but I have no clue where to start and whether this is the right thing to do...