He hasn't called me back? Does this mean he's not interested? If I text now will I seem desperate?

We've known each other 8 months and have gone out four times. At the start I told him I was looking for a friend ( I had a long relationship which hurt me when it ended). Anyhow, we lost touch for months as his mother was very ill, then we got back in contact and he told me he'd like to meet me. When I forgot to reply to him he sent me a text 'you didn't reply? don't you want to meet?' So we did meet last Monday for a coffee and had a great time for a couple of hours. I left that meeting realising that I now have feelings for him. He said to me I was welcome to stay at his place for a night or two (as there are problems with the house I'm staying in). I joked 'and where would I sleep?' He said 'on the sofa!', Anyhow, I've been to his place before and he was very respectful and gentlemanly. He asked me to call him which I did on Wednesday night, left a voicemail to call me when he can and I still havn't heard from him. I was thinking of texting him and inviting him to a concert being given my a friend of mine on Sunday. Do you think this would be too forward as he hasn't got back to me yet? Would he think I'm pushy or desperate?