If you're worried about not feeling anything then you're not a bad parent (or almost-parent). You're worried because you care.
Please talk to your midwife, feeling like this is unbelievably common and is not necessarily a reflection of how you will feel when the baby is born. Even if you do continue to feel like this, there is support available.
For context I was incredibly excited about having DS1, was totally in love with this tiny human growing inside of me, then after his birth I instantly felt the complete opposite. I suffered terribly with postnatal depression and don't think I really felt a proper maternal love for him for around 4/5 years. It was a very slow process but all turned out well in the end 
With DS2 I couldn't even register I was pregnant until I was in labour, completely ignored it, bought only the bare minimum in baby things. Funnily enough it all flipped around again when he was born and I couldn't bear to be without him. Wouldn't put him down for hours at a time, woke to every single squeak through the night etc.
How you feel now does not dictate how you will feel after birth, but worrying about your baby, or even that you may not be ready/suitable for them indicates that you do have protective feelings towards them already. Pregnancy is long and tiring. The excitement you're expecting may still come.
The most important thing is to vocalise your feelings and help yourself to understand them. Make sure you have someone (midwife, mum, a friend etc.) to support you and listen to you.
Good luck with the rest of your pregnancy!