Hi mama!
Ang egg white discharge na yan could be normal pregnancy discharge talaga, especially if di mo pa nararanasan before, pero since you're having pelvic pressure, lower back pain, at you're in that in-between zone with your dates (34-37 weeks), it's worth having your OB check it out tomorrow, which you're already doing! One of my mum friends said she had similar discharge at 36 weeks and it wasn't the mucus plug yet, she went into labor three weeks later pa lang. The real mucus plug discharge tends to be thicker, sometimes with streaks of blood or a bit brownish, hindi lang egg white.
The good news is you don't have to panic, losing the mucus plug doesn't mean labor is happening right now; some moms have it come out days or even weeks before actual contractions start. Just call your OB or go to triage if you notice a steady trickle of fluid, reduced baby movements, any bleeding, or fever, kasi those are the things that actually need attention.
For now, rest up, avoid heavy lifting (shopping at SM when you're this far along, relatable but eek!), and let your doctor guide you tomorrow based on what they see and feel. You're doing great, see you sa checkup!