Friends or more?

My friend (20M) and I (20F) have been friends since we were 2 months old. We were very close when we were younger but didn’t talk much as we grew up due to him being homeschooled and myself being at boarding school. We started talking again when I finished high school (he still had one more year) and sort of kept hanging out.

After he finished high school he started uni in the same city as I am living. I work full time after not continuing in my second year of uni but he has now just finished his second year.

About a year or 2 ago he asked me to go on a date with him. I said no because I didn’t want to ruin the friendship we had or our families feeling weird if we didn’t work out. He agreed and we didn’t speak of it again. We hang out and speak occasionally but we are both quite busy. I have had thoughts of what would have happened if I said yes or what it would be like to be with him. I have also had comments from my younger sister (freshly 18) saying why don’t we just get together. I also talked to someone and they suggested the only reason I keep feeling this way is because I am lonely (which is true. I don’t go out a lot and have never had a boyfriend) and because I may be listening to my sister.

I agreed and thought it was because I am a bit lonely but I have thought about him a bit the past week and I am not sure.

I visited him and his family last week because I went up for a holiday and it was different. I was nervous to see him. And last night I had a dream we were together. And I just keep having thoughts of what it would be like to be together.

I have no clue what I am feeling or what I should do.

Please Please Help me