Yes and NO. Having bleeding from vagina ( menses ) is a sure sign of pregnancy not being there, but in some cases it also could be a sign of an abortion.
If you are using protection always, then mostly the pregnancy may not happen doe to this protection.
So let the menses come. if you feel it is scanty or is different from your routine flow, then it could be sign of pregnancy too.
The best way to tackle this is to do a Urine
pregnancy test on a early morning sample in lab and see the result. if you have a negative UPT result. It means you are not
pregnant.
Next Steps
Protection like condoms can tear during sex and this may not be noticed by the partners. hence condom has high failure rate.
Health Tips
If you are sexually active, have PCOD , pregnancy can be avoided by taking OCPills which are designed for PCOD. These will prevent pregnancy and also make your cycles regular. How ever, it is also the best to use such pills along with condoms for double protection. Condoms also protect you from getting infections from your partner.