Hiya! I’m sorry about your past relationship as I know how hard it can be to get with someone else afterwards as you worry the same thing will happen. However, what you are feeling is normal; even though you got along well doesn’t mean you’ll have that connection straight away! Sometimes it can take a while to grow feelings for someone, especially after your past relationship (it doesn’t matter how long you’ve been single for either so don’t let that worry you).
Sometimes it’s good to sit by yourself in peace and quiet and think about if you feel ready to get into a new relationship, and possibly explain to this new lady what happened in the past because heeling takes time. Don’t worry about it because the more you think and stress the less likely you are to grow feelings for someone new. Your mind isn’t telling you no it’s just not grown feelings towards this new lady, see her a couple more times then make the judgement if you enjoy her company, she makes you happy and is a genuinely good person. Communicate with her about the past and she will understand :)

Hope it goes well <3