hi there!
first of all....relax...4 months seems like a long time, especially when u see dear aunt flo showing up like clockwork every month, but it is not too bad. it took us 6 months to get pregnant with daughter #2. it will really help if u and your husband arent stressing over it.
second...get in tune with your cycle. day 1 is the day your period starts. most women have a 28 day cycle, and the majority of women ovulate on days 8-18. so that is your window of opportunity. so, technically, u have only 1/3 of the month that u have to 'actively' try. :o)
last...u will probably hear so many different "ways" to increase your chance of pregnancy. just do whatever works for u. people told us that u had to "do it" every day. so we tried it...no baby...then someone said that u couldnt do it every day, u needed to "build up" his "supply" so u had to rest a day..hee hee ...so, the every other day thing didnt work either...then we heard the "resting" thing was a myth, u could do it all day long if u wanted...well, needless to say, that didnt work either...but husband was very very happy with our efforts;o) after a few more months of just doing what worked for us (within that 10 day fertile window) we finally got that big fat positive on the test!
have fun, relax, and let us know when u have success!
wish u all the best!
~J.