My baby had a similar problems at around 6 months.
Besides what you are already doing, when she sleeps on her back you need to put a little wedge or pillow (not soft, those are not recommended at this age), maybe a blanket folded several times and put under she sheet where she puts her head. Basically you are trying to get the baby's head to be slightly elevated so that the congestion does not get stuck, especially because it can cause ear infection.
Also, and this is really funny to say, but when my baby had that, I went grocery shopping one day and my husband was home with her. When I came back he said "The poor thing could not breath and I did not find the little pump to take off her snot, so I suck the snot out of her nose with my mouth, then spit it out."
It's funny and a little weird, and I do not know if I could do it, but after my husband' trick my baby got better as he basically blew her nose and she could breath:) Sometimes husbands do good things too!!