If you're having sex, yes you can be pregnant. If you don't want to end up pregnant and if it's not too late again, I'd say birth control and condoms would be a good idea.
Even with the negative pregnancy test I can still be pregnant?
Yes me and my partner are trying to conceive.
You're trying to conceive yet you had an abortion?
she might mean miscarriage some places and people still call them abortions even when they are not choosing to abort the baby but had a miscarriage or the baby died
To avoid confusion, you might wanna relabel it as a d&c or miscarriage. Abortion (though the proper term) implies live termination of a fetus, and many will give you negative answers.
That would clear things up a bit. I was confused why someone would have an abortion then turn around and try to get pregnant.
To the OP:
If you are having sex it's entirely possible you're pregnant. It is possible to get a false negative. If you don't trust the tests I'd say get a blood test done.