Please help! TTC is confusing me!

I’ve been on the depo injection about 18 months and I had my last one on the 12th September so my next one was due on the 12th December but I purposely didn’t go for it because me and my partner are now ready to have a baby and we have had quite a bit of sex since then. I had some vaginal bleeding and browning discharge around Christmas time but this last 2 weeks by boobs have been extremely sore and tender and have got more fuller and definitely larger. I have also had cramping pains in my lower stomach and have had the sicky feeling most mornings. Could I be pregnant or could this just be side effects to coming of the depo? Xx