You can win lane all you'd like but if your ADC just suicides your advantage is pretty much evaporated. Doesn't really feel like it matters if I play well, just matters if my ADC abuses the lead you earn early game properly.
What do you do as Soraka if your ADC just isn't very good? Just rejoined league and continually go on 80% winning streaks then 80% losing streaks, really just doesn't feel that fun anymore. Is she just not very good for solo queue?
If you're AD isn't doing well then just roam and help others whilst putting and clearing some wards in the process.
Tell your allies to bait enemies and when they engage fully and about to kill your ally flash your dirty mastery 7 and do nothing as your ally dies run up and heal them while throwing your Q to give your ally time to catch up to the enemy.
Soraka just suffers heavily lately because of a lot of Grievous Wounds sources being used everywhere (Ignite, Morellonomicon, Executioners Calling/Mortal Reminder) as well as the fact that she isn't able to outheal the damage that her allies take unless the enemy team is severely behind.
I would suggest picking up a different champion who's 60% kit isn't Healing related if you want more success (It hurts for me to say this because I main this stupid banana goat godess, and I find myself always dying just because I always have to use that last bit of W in order to ensure my allies survival just an extra second longer even if it means I will die in the process).
Swap to mid/top depending on who is doing better.
