Unfortunately she can’t tell you verbally how she feels, so you will have to observe her behavior to know.
If she already has a secure attachment to you (and she is a bit young for that to have occurred completely), she probably won’t feel “abandoned,” to use your term. Attachment is usually pretty completely established by six months, and I have always recommended waiting until a child is at least that old before going back to work. However, there is not any solid research evidence that this is necessary. Even so, it seems like a good rule of thumb to me.
There is one thing I definitely suggest to you: either use your in-laws or the sitter. It would be much easier for your baby to adjust to one sitter than two.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.