ok, great! What you can do next is pick a place you want your house at and dig a about 5 gallon bucket size hole , and dump a 5 gallon bucket of water in it. If it drains really fast , great! You might have type A soil ( like sand) and this is a good site for a septic system ( this might save you some money if you can tell the engineer or whoever will do your testing you already have a good spot) . If it does not drain at all ( type D soil, like heavy clay ) , find a new spot. Look for pines, they don't like growing in wetlands too much. If there is cypress trees, it's probably wetland, stay away from that.
Think about access, do you have a driveway? You need to get a driveway permit most likely to attach it to a public road somewhere.
Find a good general contractor , might be cheaper than hiring an engineer and talk to them about what they can do. They might already have people that can do the testing and site plans. Most counties will accept an environmental or even geotech technician to do the soil testing. What sort of building do you want to have?
When we remodeled our house in Orlando some years ago, I did the site plan, and a friend ( architect) did the house design. Do you have any friends like that maybe? You can draw the plan yourself ( what you want) and give it to them to figure out if it works and add specs. If you do not have a lot of money to work with here is a tip to make septic cheaper: only have the minimum number of bedrooms in the house ( 1 is best, 2 if you have kids) and make some other rooms and call them "office" , "den" , storage" or something not bedroom, because they go by number of bedrooms to size the septic ( or at least they used to) so it will cost much more . You can always turn the office into a bedroom later ( we did). We didn't have septic but waste water rates were based on how many bedrooms we had.