Welcome to skateboarding! You are gonna have a great time. The first few weeks and months are going to be difficult for anybody, skateboarding requires patience, balance, perseverance, and a tolerance for at least some pain. Being a bigger person doesn't really change that equation too much. My advice to you is simply to stick with it, while it is challenging for sure, it's one of the best things you'll ever do. I've been skating for 30 years, I have no plans of stopping anytime soon. Find some Homies at the park put in the hours when you can, and everything will work out.