Milestones

So after my son’s 15 month visit with the pediatrician I am finding it hard to focus on anything else. It was at that visit that I began to worry he isn’t doing some of the milestones he should be. He isn’t talking yet- he used to say mama and dada but then it went away, came back a couple months later and went away again. He makes a lot of letter sounds and tries to imitate noises he hears and finds funny. He doesn’t feel comfortable walking independently even though I know he could- he’s very cautious and can take steps independently but overall feels more secure holding something so he doesn’t fall. He’s not yet using a spoon or waving. But my husband and I both work from Home so he doesn’t have the need to wave. I don’t know. He’s not in daycare. He entertains himself a lot during the day while I work. Which I have guilt about. He gets way more time with a screen than I’d like. I feel like quitting my job and focusing on him to spend all day every day helping him learn and work on these milestones. It’s so stressful. All of it is. My job is, too. My husband doesn’t support me quitting due to finances but my son is the only thing that matters to me and he clearly needs me right now. I just am hoping for some advice or reassurance or support!!!!