Hello Welcome to HCM...
I am really sorry for your worry but I'm definitely going to help you out..
Thanks for posting your query here..
I being a surgeon, we encounter so many such cases day in and day out.
I read your question completely and have understood it well enough..
I will analyze all your points and provide necessary information..
1. How were your previous cycles?
Delay by 3 weeks is definitely not normal but is sometimes seen in few patients that come to us.
2. The symptoms that you tell
brown spotting, cramp, back ache doesn't 100% suggest
pregnancy.
This can be seen as a normal disease ailment..
3. We cannot comment about
miscarriage at this stage..
Please note the following few facts..
A. Please get an Urine pregnancy test. UPT
Various kits are available and can be done in your home itself. No need for any doctor to read this test..
Two possibilities, if it's negative then chill, you'll be fine soon..
If positive then, yes it's a confirmed pregnancy..
B. If UPT is positive then don't stop there.
Get a radiology obstetric scan done.
This will tell us, if there's Intra uterine, or ectopic pregnancy. Exact date. And many other things.
C. Miscarriage or
incomplete abortion etc.
We can see later how to go about after all these..
Hope this helps you, in case you need further assistance, please let me know.
Take care and God bless..