You do sound insecure. She gave you feedback so let's look at it.
1. If you're gonna do something that causes her to alter her routine or life in a significant way, then that's worth having a talk about. If you just want to do something nice, don't fucking ask to do it, just DO it. This includes things like making breakfast, cleaning up after yourself, or running errands for her. I.E if she says oh man I'm so busy today I have A B C D E to do then you can follow up with "oh wow you are super busy today. Don't worry, I've got dinner covered tonight. Text me about a half hour before you get home so I know when to have it ready." It shows that you care about her, and are taking charge. You sound supportive without being a doormat. If she says no thank you in some form or another, then you simply back off and say "ok np! If you need help with anything lemme know <3 "

1. Unless she's flirting in front of you or texting other men on the side don't tell her how to deal with other men. God, that's fucking annoying. It makes you insecure and it makes her feel like you don't trust her. Instead, next time, just say "yeah I can see how other men are attracted to you, you're hot!" and then move on.
   3) I would honestly talk to a sex therapist or maybe someone else can chime in.
   4) Get an honest assessment of how you dress vs other men. Are you cargo shorts and tshirt all the time? Do you dress age appropriate? I feel you on this one. I was tshirt and jeans (girl) until my mid 20s and I almost NEVER got dates. I had to suck it up and watch a bunch of youtube videos on how to dress myself and look cute before men started paying attention to me. You might need to do the same.