Am I right to be worried about these symptoms?

I have been experiencing irregular vaginal bleeding for over 2 years (as in too often - averages at one period every 2 weeks - but can be as much as every 4 weeks). I am bloated, have lower back pain, abdominal cramping and an occasional much sharper pain, a change in bowel and urine habits, nausea and general feeling of something not being quite right. I do have IBS so it had been easy to attribute my aches, pains and many of these other changes to that.

I had my last smear 2 years ago and it was all clear. In fact, this was my 10th clear smear in a row meaning I don't have to have them repeated yearly following a CIN3 result after my very first smear, aged 19 (I'm now 40 so it's taken a while).

However, in a more recent change of symptoms I now have a constant but slight vaginal discharge which is pink (so contains blood) and has lasted 2 weeks with no sign of ending before my next 2 weekly bleed. Basic blood tests have come back with subclinical hypothyroidism but I will not be medicated until after a repeat blood test in 6 months time (although I have been medicated for this same reason twice in the past). I have an abdominal ultrasound booked in next week (external) but not sure what they will actually be checking for.

How likely is it that these symptoms are as a result of some form of cancer? Having made the mistake of using Google and reading cancer symptoms on Jo's Trust it would be good to read the experiences of others.

I should add, my life is pretty stressful - I have an autistic teenager who has been medically signed off school for 2 years and still counting.  Could this be a physical response to the stress of getting my teenager the right support....maybe....hopefully?!

Thanks in advance.