Call triage as they can check if your waters have gone, especially as you are premature. I didn’t have a bloody show either when I went into labour x
Mine went at 32 weeks there was it sounds like your experience id call the maternity ward as they will do a swab to see if it is waters x
This happened to me, deftintley give triage a ring as if it was your waters, they will need to monitor you as the risk of infection increases 24 hours after your waters break (I had to be induced as waters went but no contractions etc started)
Midwife said before to put a pad on- go lye down for a bit, then stand up and if there’s a gush then you know it’s your waters as it would have pooled inside your vagina before you stand and gravity takes over. But saying that, if you’ve changed 4 times today that seems excessive to just leaking urine, so I would give triage a call for advice. They’d prob ask you what colour, is there a smell and they may want you to take your pad in for them to have a look xxx