Property investors doing single family homes?

Are there any RE investors who are going through the single family home route? So I am fairly new to REÍ and I have been taking the Single family home route. This takes a bit longer, but the properties typically go up in value a lot faster, are easier to rent, and you get more out of them. I bought my first Investment home back in 2015 and It has been a success for the last 2 years. I would like to keep going this route, but struggling to get loans. My credit score is great (770), I have enough for another down payment (20%) but lenders still can’t lend because I have around 230k in debt from the other home. I make 105k/year so my debt to income ratio is borderline. My plan was, and had always been to buy a new single family home every 3 years of around $300k,rent it for around 1600-2000/month. Repeat. I guess my question is how do you guys do it? What is your plan to success? Am I buying too soon? Am I doing anything wrong?