Getting frustrated with my supply. Please help.

I have been at this for almost 5 months now and so far bf has been a dream. He eats well, gains wieght well, no problems.

But all of a sudden my supply is going down. I am a sahm (except saturdays) so I didnt invest in an expensive pump knowing that I would be home almost always and bottle feeding would be minimal.

I am a wedding photographer so I am gone most of the day on Sat and not able to pump as much as I would feed him if I was at home. Maybe one good pumping if I am lucky. Is it possible that this is screwing up my supply for me for the rest of the week?

I owned the harmony manual pump and really liked it. I just felt lately I wasnt getting a good suction. I was trying to pump more at night after he goes to bed to help up my supply. I have him on formula on saturdays because I cant keep up with feeding him and building a supply of my own.

I am drinking red raspberry tea... and I went and bought a new pump today hoping it would have better suction. I got 2 oz's.... I now worry I am starving my child. not really... but I bet he would be happier if I was giving him more.

thoughts, suggestions, questions... this is my 3rd child but first time breastfeeding.