hey, we have similar bodies as of right now. I'm 5'4" and at 170. I don't know about the stretch mark thing, i think they're permanent, but there are ways to get them to be less noticeable. take vitamin E gel capsules, break them open and massage the oil into the stretch marks twice a day, for some people this has made them go away entirely!
and if you don't have a gym membership, take advantage of the summer and public parks! go swimming! It's such a good workout, and you wont even feel like you're working out because its enjoyable, then lay on the beach afterwords and feel good about yourself.
also, if you do want to join a gym, i dont know if they have 24 hour fitness by you, but right now theres no processing or initiation fees and its 20 dollars a month, month-to-month...which lets face it people, thats like what we spend on lattes, or one trip out to eat.
you look great! keep up the good work!