I need help on what tv antenna and amp. to buy. I live in New Bedford MA. 02740. I have a travel trailer in the yard that gets all the channels (2,4,5,6,10,11,12) Mass & RI. I put a small GE685 Yagi antenna and a Winegard LNA 200 preamplifier. Pointed the antenna 344* and all I get is channel 12. I turned the antenna all over and nothing. Do I need a bigger antenna or bigger amp.?