Assuming you are female, yes. Although these symptoms are in no way conclusive.
Everyone is different. When you are young your nipples may be hard a lot of the time. As you get older your nipples tend to become hard only when you are cold, wet or sexually aroused.
They get Cold and harden.
It means you're horny or have chills.
Take a pregnancy test. (you are most likely pregnant)
She may be pregnaant, if not, in heat.
yes are her nipples leaking
Yes as you have tried to conceive all this time, now you may be pregnant.
A dog's nipples may swell during of after her heat cycle. They can stay swollen for up to two weeks after her heat is finished. If they stay swollen longer than that, it's time to have her checked out by a vet.
Its not hard at all. When in heat they should be able to get pregnant. Sometimes on their first time they don't get pregnant. But that's rare.
Being in a cold environment can cause such a reaction.
When a girl aged 10-12 gets breasts at that time nipples feel sore because of it growth. It's natural. And when a woman is pregnant she usually feels the same.