On the verge of a breakdown

My period is due in 4 days, but for the last couple week or so I can't stop thinking I'm pregnant. I've felt fuzzy-headed, headaches and just can't stop thinking about it. Today I am nauseous and have had very light/mild spotting. I do sometimes get this a few days before my period though.

I don't want another baby and we can't afford one, we use condoms but we did have an accident 5 days before I was due to ovulate. I've done a test everyday for the last 3 days and they are all negative.

I know no-one can tell me either way but I think I'm on the verge of a nervous breakdown over it. I suffer with anxiety anyway and this is really tipping me over the edge. I don't know who to speak to or what to do as my partner doesn't understand why I'm panicking when we haven't had a positive result.

Do you think my anxiety could be making me have symptoms??

Has anyone had an abortion and regretted it when you know that you can't cope with another baby?