How can I show my daughter I do love her?

Please don't stress out about this. What she is saying is totally and completely natural. She's 8 years old - "love" to her probably means someone just giving her everything she wants.
The trap of the single parent is guilt - you feel guilty because you can't provide what you think two parents can provide. You give up your time with your children to work and a lot of times you over compensate with material things or leniency. That in turn gives your children a sense of entitlement, which can make them spoiled. How do I know? I went through the same thing with my oldest daughter.
You're her mother and you know you love her. That's enough - in time you daughter will realize the sacrifices you have made and the love you put into raising her. She just needs time to appreciate it all. Don't bend over backwards trying to prove to her the sincerity of your love - she will then expect that behavior from the rest of the world. She's going to have to accept what you give her and be happy with that, it's not going to damage or hurt her to not get her way sometimes. When my daughter younger she begged to live with my sister. Of course she wanted to - it was always fun there and she got whatever she wanted from my fun and zany sister. I was a dour old maid compared to that, lol. But with time my daughter realized what it really takes to be a parent, and now we have the utmost respect for each other. She's a great teenager.
As for you - as hard as it may sound, you're just going to have to let your daughter know that she isn't entitled to anything - even extravagant shows of love. If story time and nice houses aren't enough - tough, she's just going to have to take what she can get. If you feel that there is something more than that, take her to see a child psychologist - she might be able to express her feelings better when speaking to someone outside of the situation.
Good luck and don't worry. It'll all work out.

speaking as someone who had everything a beautiful home, anything I wanted material wise it never made me feel oved by my parents I don't think it makes anyone feel loved

lay down rules with your daughter don't always let her go places be a mom lay rules, and stick to them, hug her as you do tell her you love her at night and in the morning